diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..7dba28c
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,48 @@
+/** Localizes strings. Must be called as T("some string") or someThing.T("some string") */
+export type LocalizeString = (str: string, ...args: any[]) => string
+
+/** A single localized string */
+export interface LocalizedString {
+  /** e.g. "en" */
+  _base: string
+  /** Localizations in each language */
+  [language: string]: string
+}
+
+export interface Locale {
+  /** ISO code for locale (e.g. "en") */
+  code: string
+
+  /** Local name for locale (e.g. Espanol) */
+  name: string
+}
+
+export interface LocalizerData {
+  locales: Locale[]
+  strings: LocalizedString[]
+}
+
+/** Localizer which has a lookup of translations */
+export class Localizer {
+  /** Locale defaults to "en" */
+  constructor(data: LocalizerData, locale?: string)
+
+  /** Set the current locale */
+  setLocale(locale: string): void
+
+  getLocales(): Locale[]
+
+  /** Localize a string */
+  T: LocalizeString
+
+  /** Same as T */
+  localizeString: LocalizeString
+
+  /** Determines if a string is localized */
+  isLocalized(str: string): boolean
+}
+
+export const defaultLocalizer: Localizer
+
+/** Create a default T that does nothing */
+export const defaultT: LocalizeString
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