diff --git a/scripts/get-data.sh b/scripts/get-data.sh
index 73dbb84fc..288197629 100755
--- a/scripts/get-data.sh
+++ b/scripts/get-data.sh
@@ -76,3 +76,6 @@ do
 done
 
 echo "The local data directory ./data now contains up-to-date datasets from http://data.nextstrain.org"
+
+# TMP
+curl http://staging.nextstrain.org/zika-tutorial-metadata-via-api.json --compressed -o data/zika-tutorial-metadata-via-api.json
\ No newline at end of file
diff --git a/src/middleware/extraMetadata.js b/src/middleware/extraMetadata.js
new file mode 100644
index 000000000..4182ff7bb
--- /dev/null
+++ b/src/middleware/extraMetadata.js
@@ -0,0 +1,77 @@
+import * as types from "../actions/types";
+import { infoNotification } from "../actions/notifications";
+import { fetchJSON } from "../util/serverInteraction";
+import { changeColorBy } from "../actions/colors";
+
+/**
+ * EXPERIMENTAL ONLY -- NOT FOR PRODUCTION
+ * This function is a proof-of-principle approach for spiking in metadata
+ * via an API call, rather than storing it within the JSON.
+ * It currently only works when changing to a new colorBy.
+ * Cacheing is not implemented.
+ */
+export const extraMetadataMiddleware = (store) => (next) => async (action) => {
+
+  if (action.type === types.NEW_COLORS) {
+    const {metadata, tree} = store.getState();
+    const coloringSpecifiesApiEndpoint = metadata.colorings && metadata.colorings[action.colorBy] && metadata.colorings[action.colorBy].EXPERIMENTAL_google_sheets_id;
+    const colorScaleIsUndefined = action.colorScale.legendValues.length === 0; // stops unnecessary fetches
+    if (coloringSpecifiesApiEndpoint && colorScaleIsUndefined) {
+      store.dispatch(infoNotification({message: "Fetching colors, hold on!", details: "Should use spinner or similar UI"}));
+      try {
+        const colorByData = await getGoogleSheetData(metadata.colorings[action.colorBy].EXPERIMENTAL_google_sheets_id, action.colorBy);
+        insertDataIntoTree(tree, action.colorBy, colorByData);
+        store.dispatch(changeColorBy(action.colorBy)); // re-dispatch, the original one won't have gone through!
+      } catch (error) {
+        console.error(error);
+      }
+      return;
+    }
+  }
+  next(action); // send action to other middleware / reducers
+};
+
+
+/** get & parse data from (public) google sheets.
+ * Google is moving to v4 of their API, however that seems (?) to require API keys even to access public
+ * data. Thus i'm using the v3 API, which will go offline on Sept 30, but allows anonymous API calls.
+ * As such, the parsing function is rudimentary. We only parse the field `keyName`, but cacheing of the response
+ * (within auspice?) will make this acceptable
+ */
+async function getGoogleSheetData(id, keyName) {
+  const sheet = await fetchJSON(`https://spreadsheets.google.com/feeds/cells/${id}/1/public/full?alt=json`);
+  const cells = sheet.feed.entry.map((e) => e["gs$cell"]);
+
+  /* work out what column represents the keyName */
+  let keyColumnId;
+  try {
+    keyColumnId = (cells.filter((c) => c.row==="1" && c.inputValue===keyName)[0]).col;
+  } catch (e) {
+    console.error(`Couldn't find a column name of ${keyName} in the google sheet`);
+    throw e;
+  }
+
+  /* create a Map of strain -> keyValue out of the google sheets JSON */
+  const rowToStrain = new Map();
+  cells.filter((cell) => cell.row!=="1" && cell.col==="1") // assume strain is col 1
+    .forEach((cell) => {rowToStrain.set(cell.row, cell.inputValue);});
+  const strainMap = new Map();
+  cells.filter((cell) => cell.row!=="1" && cell.col===keyColumnId)
+    .filter((cell) => rowToStrain.has(cell.row))
+    .forEach((cell) => {
+      strainMap.set(rowToStrain.get(cell.row), cell.inputValue);
+    });
+
+  return strainMap;
+}
+
+/** this should be done in a reducer, but simply modifying the internal data within
+ * the tree is a shortcut and is possible since it's an Object.
+ */
+function insertDataIntoTree(tree, key, data) {
+  tree.nodes.forEach((n) => {
+    if (data.has(n.name)) {
+      n.node_attrs[key] = {value: data.get(n.name)};
+    }
+  });
+}
diff --git a/src/store/index.js b/src/store/index.js
index a6c34d6a6..aac38c5cc 100644
--- a/src/store/index.js
+++ b/src/store/index.js
@@ -1,12 +1,15 @@
 import { createStore, applyMiddleware, compose } from "redux";
 import thunk from "redux-thunk";
 import { changeURLMiddleware } from "../middleware/changeURL";
+import { extraMetadataMiddleware } from "../middleware/extraMetadata";
+
 import rootReducer from "../reducers";
 import { loggingMiddleware } from "../middleware/logActions"; // eslint-disable-line no-unused-vars
 
 const configureStore = (initialState) => {
   const middleware = [
     thunk,
+    extraMetadataMiddleware,
     changeURLMiddleware, // eslint-disable-line comma-dangle
     // loggingMiddleware
   ];