diff --git a/app/soapbox/utils/features.js b/app/soapbox/utils/features.js
index 0516ef02d..917653a3a 100644
--- a/app/soapbox/utils/features.js
+++ b/app/soapbox/utils/features.js
@@ -4,6 +4,19 @@ import { createSelector } from 'reselect';
 import gte from 'semver/functions/gte';
 import lt from 'semver/functions/lt';
 
+// FIXME: We have to use a dynamic import to trick Webpack into treating it as
+// optional, but this causes custom locales to become part of the main chunk.
+const importCustom = path => {
+  try {
+    return require(`custom/${path}.json`);
+  } catch(e) {
+    return {};
+  }
+};
+
+// Import custom overrides, if exists
+const overrides = importCustom('features');
+
 const any = arr => arr.some(Boolean);
 
 // For uglification
@@ -16,7 +29,7 @@ export const getFeatures = createSelector([instance => instance], instance => {
   const features = instance.getIn(['pleroma', 'metadata', 'features'], ImmutableList());
   const federation = instance.getIn(['pleroma', 'metadata', 'federation'], ImmutableMap());
 
-  return {
+  return Object.assign({
     bookmarks: any([
       v.software === MASTODON && gte(v.compatVersion, '3.1.0'),
       v.software === PLEROMA && gte(v.version, '0.9.9'),
@@ -93,7 +106,7 @@ export const getFeatures = createSelector([instance => instance], instance => {
       v.software === MASTODON && gte(v.compatVersion, '3.2.0'),
       v.software === PLEROMA && gte(v.version, '2.4.50'),
     ]),
-  };
+  }, overrides);
 });
 
 export const parseVersion = version => {
diff --git a/docs/development/build-config.md b/docs/development/build-config.md
index e5083b8a0..a5f9a741b 100644
--- a/docs/development/build-config.md
+++ b/docs/development/build-config.md
@@ -1,5 +1,45 @@
 # Build Configuration
 
+Soapbox supports compile-time customizations in the form of environment variables and a gitignored `custom/` directory.
+
+## `custom/` directory
+
+You can place files into the `custom/` directory to customize the Soapbox build.
+
+### Custom locales (`custom/locales/*.json`)
+
+It is possible to override locale messages by creating a file for each language, eg `custom/locales/en.json`.
+In this file, add only the messages you want to be overridden.
+For example:
+
+```json
+{
+  "account.posts": "Poasts",
+  "account.posts_with_replies": "Poasts & Replies",
+  "compose.submit_success": "Your poast was sent!",
+  "compose_form.publish": "Poast"
+}
+```
+
+These messages will be merged into the language file shipped with Soapbox.
+
+### Feature overrides (`custom/features.json`)
+
+You can create a file called `custom/features.json` to disable version-checking and force some features on or off.
+For example:
+
+```json
+{
+  "bookmarks": false,
+  "lists": false,
+  "quotePosts": true
+}
+```
+
+See `app/soapbox/utils/features.js` for the full list of features.
+
+## Environment variables
+
 When compiling Soapbox FE, environment variables may be passed to change the build itself.
 For example: