diff --git a/c-api/c-tests/src/test.c b/c-api/c-tests/src/test.c
index 70ce42dc..7ea22ef4 100644
--- a/c-api/c-tests/src/test.c
+++ b/c-api/c-tests/src/test.c
@@ -16,5 +16,9 @@ int run_tests() {
     subtest("Element API", element_api_test);
     subtest("Document end API", document_end_api_test);
     subtest("Memory limiting", test_memory_limiting);
-    return done_testing();
+    int res = done_testing();
+    if (res) {
+        fprintf(stderr, "\nSome tests have failed\n");
+    }
+    return res;
 }
diff --git a/c-api/c-tests/src/test_element_api.c b/c-api/c-tests/src/test_element_api.c
index 70236b18..a8171123 100644
--- a/c-api/c-tests/src/test_element_api.c
+++ b/c-api/c-tests/src/test_element_api.c
@@ -238,6 +238,114 @@ static void test_insert_content_around_element(lol_html_selector_t *selector, vo
     );
 }
 
+//-------------------------------------------------------------------------
+EXPECT_OUTPUT(
+    streaming_mutations_output_sink,
+    "&amp;before<div><!--prepend-->Hi<!--append--></div>&amp;after\xf0\x9f\x98\x82",
+    &EXPECTED_USER_DATA,
+    sizeof(EXPECTED_USER_DATA)
+);
+
+static void loltest_drop(void *user_data) {
+    int *drops = user_data;
+    (*drops)++;
+}
+
+static int loltest_write_all_callback_before(lol_html_streaming_sink_t *sink, void *user_data) {
+    int *counter = user_data;
+    ok(*counter >= 100 && *counter <= 103);
+
+    const char *before = "&before";
+    return lol_html_streaming_sink_write_str(sink, before, strlen(before), false);
+}
+
+static int loltest_write_all_callback_after(lol_html_streaming_sink_t *sink, void *user_data) {
+    int *counter = user_data;
+    ok(*counter >= 100 && *counter <= 103);
+
+    const char *after = "&after";
+    const char emoji[] = {0xf0,0x9f,0x98,0x82};
+    return lol_html_streaming_sink_write_str(sink, after, strlen(after), false) ||
+        lol_html_streaming_sink_write_str(sink, emoji, 4, false);
+}
+
+static int loltest_write_all_callback_prepend(lol_html_streaming_sink_t *sink, void *user_data) {
+    int *counter = user_data;
+    ok(*counter >= 100 && *counter <= 103);
+
+    const char *prepend1 = "<!--pre";
+    const char *prepend2 = "pend-->";
+    return lol_html_streaming_sink_write_str(sink, prepend1, strlen(prepend1), true) ||
+        lol_html_streaming_sink_write_str(sink, prepend2, strlen(prepend2), true);
+}
+
+static int loltest_write_all_callback_append(lol_html_streaming_sink_t *sink, void *user_data) {
+    int *counter = user_data;
+    ok(*counter >= 100 && *counter <= 103);
+
+    const char *append = "<!--append-->";
+    return lol_html_streaming_sink_write_str(sink, append, strlen(append), true);
+}
+
+static lol_html_rewriter_directive_t streaming_mutations_around_element(
+    lol_html_element_t *element,
+    void *user_data
+) {
+    note("Stream before/prepend");
+    ok(!lol_html_element_streaming_before(element, &(lol_html_streaming_handler_t){
+        .write_all_callback = loltest_write_all_callback_before,
+        .user_data = user_data,
+        .drop_callback = loltest_drop,
+    }));
+    ok(!lol_html_element_streaming_prepend(element, &(lol_html_streaming_handler_t){
+        .write_all_callback = loltest_write_all_callback_prepend,
+        .user_data = user_data,
+        // tests null drop callback
+    }));
+    note("Stream after/append");
+    ok(!lol_html_element_streaming_append(element, &(lol_html_streaming_handler_t){
+        .write_all_callback = loltest_write_all_callback_append,
+        .user_data = user_data,
+        .drop_callback = loltest_drop,
+    }));
+    ok(!lol_html_element_streaming_after(element, &(lol_html_streaming_handler_t){
+        .write_all_callback = loltest_write_all_callback_after,
+        .user_data = user_data,
+        .drop_callback = loltest_drop,
+    }));
+
+    return LOL_HTML_CONTINUE;
+}
+
+static void test_streaming_mutations_around_element(lol_html_selector_t *selector, void *user_data) {
+    UNUSED(user_data);
+    lol_html_rewriter_builder_t *builder = lol_html_rewriter_builder_new();
+
+    int drop_count = 100;
+
+    int err = lol_html_rewriter_builder_add_element_content_handlers(
+        builder,
+        selector,
+        &streaming_mutations_around_element,
+        &drop_count,
+        NULL,
+        NULL,
+        NULL,
+        NULL
+    );
+
+    ok(!err);
+
+    run_rewriter(
+        builder,
+        "<div>Hi</div>",
+        streaming_mutations_output_sink,
+        user_data
+    );
+
+    ok(drop_count == 103); // one has no drop callback on purpose
+}
+
 //-------------------------------------------------------------------------
 EXPECT_OUTPUT(
     set_element_inner_content_output_sink,
@@ -706,6 +814,7 @@ void element_api_test() {
         test_iterate_attributes(selector, &user_data);
         test_get_and_modify_attributes(selector, &user_data);
         test_insert_content_around_element(selector, &user_data);
+        test_streaming_mutations_around_element(selector, &user_data);
 
         lol_html_selector_free(selector);
     }
diff --git a/c-api/cbindgen.toml b/c-api/cbindgen.toml
new file mode 100644
index 00000000..bfa2aae8
--- /dev/null
+++ b/c-api/cbindgen.toml
@@ -0,0 +1,16 @@
+# To generate a header:
+#
+# cargo expand > tmp.rs
+# cbindgen tmp.rs
+
+language = "C"
+tab_width = 4
+documentation = true
+documentation_style = "c99"
+documentation_length = "full"
+
+[export]
+prefix = "lol_html_"
+
+[export.mangle]
+rename_types = "SnakeCase"
diff --git a/c-api/include/lol_html.h b/c-api/include/lol_html.h
index 54e5e5c1..69e9fcf5 100644
--- a/c-api/include/lol_html.h
+++ b/c-api/include/lol_html.h
@@ -30,6 +30,7 @@ typedef struct lol_html_Element lol_html_element_t;
 typedef struct lol_html_AttributesIterator lol_html_attributes_iterator_t;
 typedef struct lol_html_Attribute lol_html_attribute_t;
 typedef struct lol_html_Selector lol_html_selector_t;
+typedef struct lol_html_CStreamingHandlerSink lol_html_streaming_sink_t;
 
 // Library-allocated UTF8 string fat pointer.
 //
@@ -116,6 +117,30 @@ typedef lol_html_rewriter_directive_t (*lol_html_end_tag_handler_t)(
     void *user_data
 );
 
+// For use with streaming content handlers.
+//
+// Safety: the user data and the callbacks must be safe to use from a different thread (e.g. can't rely on thread-local storage).
+// It doesn't have to be `Sync`, it will be used only by one thread at a time.
+//
+// Handler functions copy this struct. It can (and should) be created on the stack.
+typedef struct lol_html_CStreamingHandler {
+    // Anything you like
+    void *user_data;
+    // Called when the handler is supposed to produce its output. Return `0` for success.
+    // The `sink` argument is guaranteed non-`NULL`. It is valid only for the duration of this call, and can only be used on the same thread.
+    // The sink is for [`lol_html_streaming_sink_write_str`].
+    // `user_data` comes from this struct.
+    //
+    // `write_all_callback` must not be `NULL`.
+    int (*write_all_callback)(lol_html_streaming_sink_t *sink, void *user_data);
+    // Called exactly once, after the last use of this handler.
+    // It may be `NULL`.
+    // `user_data` comes from this struct.
+    void (*drop_callback)(void *user_data);
+    // *Always* initialize to `NULL`.
+    void *reserved;
+} lol_html_streaming_handler_t;
+
 // Selector
 //---------------------------------------------------------------------
 
@@ -792,6 +817,209 @@ int lol_html_doc_end_append(
     bool is_html
 );
 
+
+
+//[`Element::streaming_prepend`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`element`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_element_streaming_prepend(lol_html_element_t *element,
+                                       lol_html_streaming_handler_t *streaming_writer);
+
+//[`Element::streaming_append`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`element`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_element_streaming_append(lol_html_element_t *element,
+                                      lol_html_streaming_handler_t *streaming_writer);
+
+//[`Element::streaming_before`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`element`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_element_streaming_before(lol_html_element_t *element,
+                                      lol_html_streaming_handler_t *streaming_writer);
+
+//[`Element::streaming_after`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`element`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_element_streaming_after(lol_html_element_t *element,
+                                     lol_html_streaming_handler_t *streaming_writer);
+
+//[`Element::streaming_set_inner_content`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`element`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_element_streaming_set_inner_content(lol_html_element_t *element,
+                                                 lol_html_streaming_handler_t *streaming_writer);
+
+//[`Element::streaming_replace`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`element`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_element_streaming_replace(lol_html_element_t *element,
+                                       lol_html_streaming_handler_t *streaming_writer);
+
+//[`EndTag::streaming_before`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`end_tag`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_end_tag_streaming_before(lol_html_end_tag_t *end_tag,
+                                      lol_html_streaming_handler_t *streaming_writer);
+
+//[`EndTag::streaming_after`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`end_tag`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_end_tag_streaming_after(lol_html_end_tag_t *end_tag,
+                                     lol_html_streaming_handler_t *streaming_writer);
+
+//[`EndTag::streaming_replace`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`end_tag`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_end_tag_streaming_replace(lol_html_end_tag_t *end_tag,
+                                       lol_html_streaming_handler_t *streaming_writer);
+
+
+//[`TextChunk::streaming_before`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`text_chunk`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_text_chunk_streaming_before(lol_html_text_chunk_t *text_chunk,
+                                         lol_html_streaming_handler_t *streaming_writer);
+
+//[`TextChunk::streaming_after`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`text_chunk`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_text_chunk_streaming_after(lol_html_text_chunk_t *text_chunk,
+                                        lol_html_streaming_handler_t *streaming_writer);
+
+//[`TextChunk::streaming_replace`]
+//
+// The [`CStreamingHandler`] contains callbacks that will be called
+// when the content needs to be written.
+//
+// `streaming_writer` is copied immediately, and doesn't have a stable address.
+// `streaming_writer` may be used from another thread (`Send`), but it's only going
+// to be used by one thread at a time (`!Sync`).
+//
+//`text_chunk`
+// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+//
+// Returns 0 on success.
+int lol_html_text_chunk_streaming_replace(lol_html_text_chunk_t *text_chunk,
+                                          lol_html_streaming_handler_t *streaming_writer);
+
+// Write another piece of UTF-8 data to the output. Returns `0` on success, and `-1` if it wasn't valid UTF-8.
+// All pointers must be non-NULL.
+int lol_html_streaming_sink_write_str(lol_html_streaming_sink_t *sink,
+                                         const char *string_utf8,
+                                         size_t string_utf8_len,
+                                         bool is_html);
+
+
 #if defined(__cplusplus)
 }  // extern C
 #endif
diff --git a/c-api/src/comment.rs b/c-api/src/comment.rs
index 81c4e056..25707318 100644
--- a/c-api/src/comment.rs
+++ b/c-api/src/comment.rs
@@ -19,45 +19,16 @@ pub extern "C" fn lol_html_comment_text_set(
     0
 }
 
-#[no_mangle]
-pub extern "C" fn lol_html_comment_before(
-    comment: *mut Comment,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { comment.before(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_comment_after(
-    comment: *mut Comment,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { comment.after(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_comment_replace(
-    comment: *mut Comment,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { comment.replace(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_comment_remove(comment: *mut Comment) {
-    to_ref_mut!(comment).remove();
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_comment_is_removed(comment: *const Comment) -> bool {
-    to_ref!(comment).removed()
-}
+impl_content_mutation_handlers! { comment: Comment [
+    lol_html_comment_before => before,
+    lol_html_comment_after => after,
+    lol_html_comment_replace => replace,
+    @VOID lol_html_comment_remove => remove,
+    @BOOL lol_html_comment_is_removed => removed,
+    @STREAM lol_html_comment_streaming_before => streaming_before,
+    @STREAM lol_html_comment_streaming_after => streaming_after,
+    @STREAM lol_html_comment_streaming_replace => streaming_replace,
+] }
 
 #[no_mangle]
 pub extern "C" fn lol_html_comment_user_data_set(comment: *mut Comment, user_data: *mut c_void) {
diff --git a/c-api/src/doctype.rs b/c-api/src/doctype.rs
index cfa30e4c..3afcf38e 100644
--- a/c-api/src/doctype.rs
+++ b/c-api/src/doctype.rs
@@ -25,12 +25,7 @@ pub extern "C" fn lol_html_doctype_user_data_get(doctype: *const Doctype) -> *mu
     get_user_data!(doctype)
 }
 
-#[no_mangle]
-pub extern "C" fn lol_html_doctype_remove(doctype: *mut Doctype) {
-    to_ref_mut!(doctype).remove();
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_doctype_is_removed(doctype: *const Doctype) -> bool {
-    to_ref!(doctype).removed()
-}
+impl_content_mutation_handlers! { doctype: Doctype [
+    @VOID lol_html_doctype_remove => remove,
+    @BOOL lol_html_doctype_is_removed => removed,
+] }
diff --git a/c-api/src/document_end.rs b/c-api/src/document_end.rs
index 6bd9eee5..566d7f2e 100644
--- a/c-api/src/document_end.rs
+++ b/c-api/src/document_end.rs
@@ -1,11 +1,5 @@
 use super::*;
 
-#[no_mangle]
-pub extern "C" fn lol_html_doc_end_append(
-    document_end: *mut DocumentEnd,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { document_end.append(content, content_len, is_html) }
-}
+impl_content_mutation_handlers! { doc_end: DocumentEnd [
+    lol_html_doc_end_append => append,
+] }
diff --git a/c-api/src/element.rs b/c-api/src/element.rs
index 897b70a6..28f1f20b 100644
--- a/c-api/src/element.rs
+++ b/c-api/src/element.rs
@@ -29,16 +29,6 @@ pub extern "C" fn lol_html_element_tag_name_set(
     0
 }
 
-#[no_mangle]
-pub extern "C" fn lol_html_element_is_self_closing(element: *mut Element) -> bool {
-    to_ref!(element).is_self_closing()
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_element_can_have_content(element: *mut Element) -> bool {
-    to_ref!(element).can_have_content()
-}
-
 #[no_mangle]
 pub extern "C" fn lol_html_element_namespace_uri_get(element: *mut Element) -> *const c_char {
     let element = to_ref!(element);
@@ -157,80 +147,25 @@ pub extern "C" fn lol_html_element_remove_attribute(
     0
 }
 
-#[no_mangle]
-pub extern "C" fn lol_html_element_before(
-    element: *mut Element,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { element.before(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_element_prepend(
-    element: *mut Element,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { element.prepend(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_element_append(
-    element: *mut Element,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { element.append(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_element_after(
-    element: *mut Element,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { element.after(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_element_set_inner_content(
-    element: *mut Element,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { element.set_inner_content(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_element_replace(
-    element: *mut Element,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { element.replace(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_element_remove(element: *mut Element) {
-    to_ref_mut!(element).remove();
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_element_remove_and_keep_content(element: *mut Element) {
-    to_ref_mut!(element).remove_and_keep_content();
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_element_is_removed(element: *mut Element) -> bool {
-    to_ref_mut!(element).removed()
-}
+impl_content_mutation_handlers! { element: Element [
+    lol_html_element_prepend => prepend,
+    lol_html_element_append => append,
+    lol_html_element_before => before,
+    lol_html_element_after => after,
+    lol_html_element_set_inner_content => set_inner_content,
+    lol_html_element_replace => replace,
+    @VOID lol_html_element_remove => remove,
+    @VOID lol_html_element_remove_and_keep_content => remove_and_keep_content,
+    @BOOL lol_html_element_is_removed => removed,
+    @BOOL lol_html_element_is_self_closing => is_self_closing,
+    @BOOL lol_html_element_can_have_content => can_have_content,
+    @STREAM lol_html_element_streaming_prepend => streaming_prepend,
+    @STREAM lol_html_element_streaming_append => streaming_append,
+    @STREAM lol_html_element_streaming_before => streaming_before,
+    @STREAM lol_html_element_streaming_after => streaming_after,
+    @STREAM lol_html_element_streaming_set_inner_content => streaming_set_inner_content,
+    @STREAM lol_html_element_streaming_replace => streaming_replace,
+] }
 
 #[no_mangle]
 pub extern "C" fn lol_html_element_user_data_set(element: *mut Element, user_data: *mut c_void) {
@@ -274,30 +209,15 @@ pub extern "C" fn lol_html_element_clear_end_tag_handlers(element: *mut Element)
     }
 }
 
-#[no_mangle]
-pub extern "C" fn lol_html_end_tag_before(
-    end_tag: *mut EndTag,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { end_tag.before(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_end_tag_after(
-    end_tag: *mut EndTag,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { end_tag.after(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_end_tag_remove(end_tag: *mut EndTag) {
-    to_ref_mut!(end_tag).remove();
-}
+impl_content_mutation_handlers! { end_tag: EndTag [
+    lol_html_end_tag_before => before,
+    lol_html_end_tag_after => after,
+    lol_html_end_tag_replace => replace,
+    @VOID lol_html_end_tag_remove => remove,
+    @STREAM lol_html_end_tag_streaming_before => streaming_before,
+    @STREAM lol_html_end_tag_streaming_after => streaming_after,
+    @STREAM lol_html_end_tag_streaming_replace => streaming_replace,
+] }
 
 #[no_mangle]
 pub extern "C" fn lol_html_end_tag_name_get(end_tag: *mut EndTag) -> Str {
diff --git a/c-api/src/errors.rs b/c-api/src/errors.rs
index 9e7b4f87..27413e8c 100644
--- a/c-api/src/errors.rs
+++ b/c-api/src/errors.rs
@@ -11,3 +11,12 @@ pub extern "C" fn lol_html_take_last_error() -> Str {
 
     Str::from_opt(err.map(|e| e.to_string()))
 }
+
+#[derive(Error, Debug, Eq, PartialEq, Copy, Clone)]
+pub enum CStreamingHandlerError {
+    #[error("Not all fields of the struct were initialized")]
+    Uninitialized,
+
+    #[error("write_all_callback reported error: {0}")]
+    HandlerError(c_int),
+}
diff --git a/c-api/src/lib.rs b/c-api/src/lib.rs
index b41d4662..04523d7d 100644
--- a/c-api/src/lib.rs
+++ b/c-api/src/lib.rs
@@ -1,3 +1,4 @@
+pub use crate::streaming::CStreamingHandler;
 use libc::{c_char, c_int, c_void, size_t};
 use lol_html::html_content::*;
 use lol_html::*;
@@ -81,6 +82,94 @@ macro_rules! unwrap_or_ret_null {
     };
 }
 
+macro_rules! impl_content_mutation_handlers {
+    ($name:ident: $typ:ty [ $($(@$kind:ident)? $fn_name:ident => $method:ident),+$(,)? ]) => {
+        $(
+            // stable Rust can't concatenate idents, so fn_name must be written out manually,
+            // but it is possible to compare concatenated strings.
+            #[cfg(debug_assertions)]
+            const _: () = {
+                let expected_fn_name_prefix = concat!("lol_html_", stringify!($name), "_").as_bytes();
+                let fn_name = stringify!($fn_name).as_bytes();
+                // removed vs is_removed prevents exact comparison
+                assert!(fn_name.len() >= expected_fn_name_prefix.len() + (stringify!($method).len()), stringify!($fn_name));
+                let mut i = 0;
+                while i < expected_fn_name_prefix.len() {
+                    assert!(expected_fn_name_prefix[i] == fn_name[i], stringify!($fn_name));
+                    i += 1;
+                }
+            };
+            impl_content_mutation_handlers! { IMPL $($kind)? $name: $typ, $fn_name => $method }
+        )+
+    };
+    (IMPL $name:ident: $typ:ty, $fn_name:ident => $method:ident) => {
+        #[doc = concat!("[`", stringify!($typ), "::", stringify!($method), "`]")]
+        ///
+        /// The `content` must be a valid UTF-8 string. It's copied immediately.
+        /// If `is_html` is `true`, then the `content` will be written without HTML-escaping.
+        ///
+        #[doc = concat!("`", stringify!($name), "`")]
+        /// must be valid and non-`NULL`. If `content` is `NULL`, an error will be reported.
+        ///
+        /// Returns 0 on success.
+        #[no_mangle]
+        pub unsafe extern "C" fn $fn_name(
+            $name: *mut $typ,
+            content: *const c_char,
+            content_len: size_t,
+            is_html: bool,
+        ) -> c_int {
+            content_insertion_fn_body! { $name.$method(content, content_len, is_html) }
+        }
+    };
+    (IMPL STREAM $name:ident: $typ:ty, $fn_name:ident => $method:ident) => {
+        #[doc = concat!("[`", stringify!($typ), "::", stringify!($method), "`]")]
+        ///
+        /// The [`CStreamingHandler`] contains callbacks that will be called
+        /// when the content needs to be written.
+        ///
+        /// `streaming_writer` is copied immediately, and doesn't have a stable address.
+        /// `streaming_writer` may be used from another thread (`Send`), but it's only going
+        /// to be used by one thread at a time (`!Sync`).
+        ///
+        #[doc = concat!("`", stringify!($name), "`")]
+        /// must be valid and non-`NULL`. If `streaming_writer` is `NULL`, an error will be reported.
+        ///
+        /// Returns 0 on success.
+        #[no_mangle]
+        pub unsafe extern "C" fn $fn_name(
+            $name: *mut $typ,
+            streaming_writer: *mut CStreamingHandler,
+        ) -> c_int {
+            content_insertion_fn_body! { $name.$method(streaming_writer) }
+        }
+    };
+    (IMPL VOID $name:ident: $typ:ty, $fn_name:ident => $method:ident) => {
+        #[doc = concat!("[`", stringify!($typ), "::", stringify!($method), "`]")]
+        ///
+        #[doc = concat!("`", stringify!($name), "`")]
+        /// must be valid and non-`NULL`.
+        #[no_mangle]
+        pub unsafe extern "C" fn $fn_name(
+            $name: *mut $typ,
+        ) {
+            to_ref_mut!($name).$method();
+        }
+    };
+    (IMPL BOOL $name:ident: $typ:ty, $fn_name:ident => $method:ident) => {
+        #[doc = concat!("[`", stringify!($typ), "::", stringify!($method), "`]")]
+        ///
+        #[doc = concat!("`", stringify!($name), "`")]
+        /// must be valid and non-`NULL`. Returns `_Bool`.
+        #[no_mangle]
+        pub unsafe extern "C" fn $fn_name(
+            $name: *mut $typ,
+        ) -> bool {
+            to_ref_mut!($name).$method()
+        }
+    };
+}
+
 macro_rules! content_insertion_fn_body {
     ($target:ident.$method:ident($content:ident, $content_len:ident, $is_html:ident)) => {{
         let target = to_ref_mut!($target);
@@ -97,6 +186,24 @@ macro_rules! content_insertion_fn_body {
 
         0
     }};
+    ($target:ident.$method:ident($handler:expr)) => {{
+        let handler_ptr: *mut CStreamingHandler = $handler;
+        if unsafe { handler_ptr.as_ref() }.is_none_or(|handler| !handler.reserved.is_null()) {
+            // we can't even safely call drop callback on this
+            return -1;
+        }
+        // Taking ownership of the CStreamingHandler
+        let handler: Box<CStreamingHandler> = Box::new(unsafe { handler_ptr.read() });
+        if handler.write_all_callback.is_none() {
+            return -1;
+        }
+        if let Some(target) = unsafe { $target.as_mut() } {
+            target.$method(handler);
+            0
+        } else {
+            -1
+        }
+    }};
 }
 
 macro_rules! get_user_data {
@@ -109,16 +216,17 @@ macro_rules! get_user_data {
     };
 }
 
-mod comment;
-mod doctype;
-mod document_end;
-mod element;
-mod errors;
-mod rewriter;
-mod rewriter_builder;
-mod selector;
-mod string;
-mod text_chunk;
+pub mod comment;
+pub mod doctype;
+pub mod document_end;
+pub mod element;
+pub mod errors;
+pub mod rewriter;
+pub mod rewriter_builder;
+pub mod selector;
+pub mod streaming;
+pub mod string;
+pub mod text_chunk;
 
 pub use self::string::Str;
 
diff --git a/c-api/src/streaming.rs b/c-api/src/streaming.rs
new file mode 100644
index 00000000..76a1003a
--- /dev/null
+++ b/c-api/src/streaming.rs
@@ -0,0 +1,85 @@
+use super::*;
+use crate::errors::CStreamingHandlerError;
+use lol_html::html_content::StreamingHandler;
+use lol_html::html_content::StreamingHandlerSink;
+
+/// Opaque type from C's perspective
+pub type CStreamingHandlerSink<'tmp> = StreamingHandlerSink<'tmp>;
+
+/// Write another piece of UTF-8 data to the output. Returns `0` on success, and `-1` if it wasn't valid UTF-8.
+/// All pointers must be non-NULL.
+#[no_mangle]
+pub unsafe extern "C" fn lol_html_streaming_sink_write_str(
+    sink: *mut CStreamingHandlerSink<'_>,
+    string_utf8: *const c_char,
+    string_utf8_len: size_t,
+    is_html: bool,
+) -> c_int {
+    let sink = to_ref_mut!(sink);
+    let content = unwrap_or_ret_err_code! { to_str!(string_utf8, string_utf8_len) };
+    let is_html = if is_html {
+        ContentType::Html
+    } else {
+        ContentType::Text
+    };
+
+    sink.write_str(content, is_html);
+    0
+}
+
+/// Safety: the user data and the callbacks must be safe to use from a different thread (e.g. can't rely on thread-local storage).
+/// It doesn't have to be `Sync`, it will be used only by one thread at a time.
+///
+/// Handler functions copy this struct. It can (and should) be created on the stack.
+#[repr(C)]
+pub struct CStreamingHandler {
+    /// Anything you like
+    pub user_data: *mut c_void,
+    /// Called when the handler is supposed to produce its output. Return `0` for success.
+    /// The `sink` argument is guaranteed non-`NULL`. It is valid only for the duration of this call, and can only be used on the same thread.
+    /// The sink is for [`lol_html_streaming_sink_write_str`].
+    /// `user_data` comes from this struct.
+    /// `write_all_callback` must not be `NULL`.
+    pub write_all_callback: Option<
+        unsafe extern "C" fn(sink: &mut CStreamingHandlerSink<'_>, user_data: *mut c_void) -> c_int,
+    >,
+    /// Called exactly once, after the last use of this handler.
+    /// `user_data` comes from this struct.
+    /// May be `NULL`.
+    pub drop_callback: Option<unsafe extern "C" fn(user_data: *mut c_void)>,
+    /// *Always* initialize to `NULL`.
+    pub reserved: *mut c_void,
+}
+
+// It's up to C to obey this
+unsafe impl Send for CStreamingHandler {}
+
+impl StreamingHandler for CStreamingHandler {
+    fn write_all(
+        self: Box<Self>,
+        sink: &mut StreamingHandlerSink<'_>,
+    ) -> Result<(), Box<(dyn std::error::Error + Send + Sync)>> {
+        if !self.reserved.is_null() {
+            return Err(CStreamingHandlerError::Uninitialized.into());
+        }
+        let cb = self
+            .write_all_callback
+            .ok_or(CStreamingHandlerError::Uninitialized)?;
+        let res = unsafe { (cb)(sink, self.user_data) };
+        if res == 0 {
+            Ok(())
+        } else {
+            Err(CStreamingHandlerError::HandlerError(res).into())
+        }
+    }
+}
+
+impl Drop for CStreamingHandler {
+    fn drop(&mut self) {
+        if let Some(cb) = self.drop_callback {
+            unsafe {
+                cb(self.user_data);
+            }
+        }
+    }
+}
diff --git a/c-api/src/text_chunk.rs b/c-api/src/text_chunk.rs
index 76074b3a..31cb03ae 100644
--- a/c-api/src/text_chunk.rs
+++ b/c-api/src/text_chunk.rs
@@ -22,50 +22,17 @@ pub extern "C" fn lol_html_text_chunk_content_get(chunk: *mut TextChunk) -> Text
     TextChunkContent::new(to_ref!(chunk))
 }
 
-#[no_mangle]
-pub extern "C" fn lol_html_text_chunk_is_last_in_text_node(chunk: *mut TextChunk) -> bool {
-    to_ref!(chunk).last_in_text_node()
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_text_chunk_before(
-    chunk: *mut TextChunk,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { chunk.before(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_text_chunk_after(
-    chunk: *mut TextChunk,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { chunk.after(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_text_chunk_replace(
-    chunk: *mut TextChunk,
-    content: *const c_char,
-    content_len: size_t,
-    is_html: bool,
-) -> c_int {
-    content_insertion_fn_body! { chunk.replace(content, content_len, is_html) }
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_text_chunk_remove(chunk: *mut TextChunk) {
-    to_ref_mut!(chunk).remove();
-}
-
-#[no_mangle]
-pub extern "C" fn lol_html_text_chunk_is_removed(chunk: *const TextChunk) -> bool {
-    to_ref!(chunk).removed()
-}
+impl_content_mutation_handlers! { text_chunk: TextChunk [
+    lol_html_text_chunk_before => before,
+    lol_html_text_chunk_after => after,
+    lol_html_text_chunk_replace => replace,
+    @VOID lol_html_text_chunk_remove => remove,
+    @BOOL lol_html_text_chunk_is_removed => removed,
+    @BOOL lol_html_text_chunk_is_last_in_text_node => last_in_text_node,
+    @STREAM lol_html_text_chunk_streaming_before => streaming_before,
+    @STREAM lol_html_text_chunk_streaming_after => streaming_after,
+    @STREAM lol_html_text_chunk_streaming_replace => streaming_replace,
+] }
 
 #[no_mangle]
 pub extern "C" fn lol_html_text_chunk_user_data_set(chunk: *mut TextChunk, user_data: *mut c_void) {