diff --git a/.env b/.env
index 517b5fd2..6a6d39b2 100644
--- a/.env
+++ b/.env
@@ -1,5 +1,6 @@
 VITE_DEFAULT_PUBKEYS=06639a386c9c1014217622ccbcf40908c4f1a0c33e23f8d6d68f4abf655f8f71,266815e0c9210dfa324c6cba3573b14bee49da4209a9456f9484e5106cd408a5,391819e2f2f13b90cac7209419eb574ef7c0d1f4e81867fc24c47a3ce5e8a248,3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d,3f770d65d3a764a9c5cb503ae123e62ec7598ad035d836e2a810f3877a745b24,55f04590674f3648f4cdc9dc8ce32da2a282074cd0b020596ee033d12d385185,58c741aa630c2da35a56a77c1d05381908bd10504fdd2d8b43f725efa6d23196,61066504617ee79387021e18c89fb79d1ddbc3e7bff19cf2298f40466f8715e9,6389be6491e7b693e9f368ece88fcd145f07c068d2c1bbae4247b9b5ef439d32,63fe6318dc58583cfe16810f86dd09e18bfd76aabc24a0081ce2856f330504ed,6e75f7972397ca3295e0f4ca0fbc6eb9cc79be85bafdd56bd378220ca8eee74e,76c71aae3a491f1d9eec47cba17e229cda4113a0bbb6e6ae1776d7643e29cafa,7fa56f5d6962ab1e3cd424e758c3002b8665f7b0d8dcee9fe9e288d7751ac194,82341f882b6eabcd2ba7f1ef90aad961cf074af15b9ef44a09f9d2a8fbfbe6a2,84dee6e676e5bb67b4ad4e042cf70cbd8681155db535942fcc6a0533858a7240,97c70a44366a6535c145b333f973ea86dfdc2d7a99da618c40c64705ad98e322,b676ded7c768d66a757aa3967b1243d90bf57afb09d1044d3219d8d424e4aea0,dace63b00c42e6e017d00dd190a9328386002ff597b841eb5ef91de4f1ce8491,eeb11961b25442b16389fe6c7ebea9adf0ac36dd596816ea7119e521b8821b9e,fe7f6bc6f7338b76bbf80db402ade65953e20b2f23e66e898204b63cc42539a3
 VITE_DEFAULT_BLOSSOM_SERVERS=https://blossom.primal.net/
+VITE_DEFAULT_SPACES=https://chat.flotilla.social/
 VITE_POMADE_SIGNERS=https://pomade.coracle.social,https://pomade.fiatjaf.com,https://pomade.nostrver.se,https://pomade.scuttle.works
 VITE_PLATFORM_URL=https://app.flotilla.social
 VITE_PLATFORM_TERMS=https://flotilla.social/terms
diff --git a/README.md b/README.md
index 529588c4..72053fe3 100644
--- a/README.md
+++ b/README.md
@@ -8,13 +8,34 @@ If you would like to be interoperable with Flotilla, please check out this guide
 
 You can also optionally create an `.env.local` file and populate it with the following environment variables (see `.env.template` for examples):
 
-- `VITE_DEFAULT_PUBKEYS` - A comma-separated list of hex pubkeys for bootstrapping web of trust
+**Platform branding**
 - `VITE_PLATFORM_URL` - The url where the app will be hosted
 - `VITE_PLATFORM_NAME` - The name of the app
 - `VITE_PLATFORM_LOGO` - A logo url for the app. Can be a local path or https link. Must be a PNG file.
-- `VITE_PLATFORM_RELAYS` - A list of comma-separated relay urls that will make flotilla operate in "platform mode". Disables all space browse/add/select functionality and makes the first platform relay the home page.
 - `VITE_PLATFORM_ACCENT` - A hex color for the app's accent color
 - `VITE_PLATFORM_DESCRIPTION` - A description of the app
+- `VITE_PLATFORM_TERMS` - URL to your terms of service page
+- `VITE_PLATFORM_PRIVACY` - URL to your privacy policy page
+
+**Platform mode**
+- `VITE_PLATFORM_RELAYS` - A comma-separated list of relay urls that will make flotilla operate in "platform mode". Disables all space browse/add/select functionality and makes the first platform relay the home page.
+
+**Defaults**
+- `VITE_DEFAULT_PUBKEYS` - A comma-separated list of hex pubkeys for bootstrapping web of trust
+- `VITE_DEFAULT_SPACES` - A comma-separated list of relay urls that new users will be automatically joined to on signup
+- `VITE_DEFAULT_RELAYS` - A comma-separated list of relay urls used as default outbox/inbox relays
+- `VITE_DEFAULT_MESSAGING_RELAYS` - A comma-separated list of relay urls used for encrypted direct messages
+- `VITE_DEFAULT_BLOSSOM_SERVERS` - A comma-separated list of blossom server urls used for file uploads
+
+**Infrastructure**
+- `VITE_INDEXER_RELAYS` - A comma-separated list of relay urls used for user profile/key lookup
+- `VITE_SIGNER_RELAYS` - A comma-separated list of relay urls used for NIP-55 remote signers
+- `VITE_BLOCKED_RELAYS` - A comma-separated list of relay urls that will be blocked
+- `VITE_PUSH_SERVER` - URL of the push notification server
+- `VITE_PUSH_BRIDGE` - WebSocket URL of the push notification relay bridge
+- `VITE_VAPID_PUBLIC_KEY` - VAPID public key for web push notifications
+- `VITE_POMADE_SIGNERS` - A comma-separated list of Pomade signer server URLs (3+ required to enable email signup)
+- `VITE_THUMBNAIL_URL` - URL of the image thumbnail service
 
 These values **won't** be used for a built version. Instead, env variables should be provided to `build.sh` directly or to the built container.
 
diff --git a/src/app/components/SignUp.svelte b/src/app/components/SignUp.svelte
index 5fa9bc51..16e92176 100644
--- a/src/app/components/SignUp.svelte
+++ b/src/app/components/SignUp.svelte
@@ -22,8 +22,10 @@
     INDEXER_RELAYS,
     DEFAULT_RELAYS,
     DEFAULT_MESSAGING_RELAYS,
+    DEFAULT_SPACES,
   } from "@app/env"
   import {setChecked} from "@app/notifications"
+  import {setSpaces} from "@app/groups"
   import {loginWithPomade} from "@app/pomade"
   import {pushModal, clearModals} from "@app/modal"
 
@@ -52,6 +54,9 @@
     // Save the user's profile
     initProfile(getKey<Profile>("signup.profile")!)
 
+    // Auto-join default spaces
+    setSpaces(DEFAULT_SPACES)
+
     // Don't show any notifications for old content
     setChecked("*")
 
diff --git a/src/app/env.ts b/src/app/env.ts
index c37ecd89..b5b635d0 100644
--- a/src/app/env.ts
+++ b/src/app/env.ts
@@ -46,6 +46,8 @@ export const POMADE_SIGNERS = fromCsv(import.meta.env.VITE_POMADE_SIGNERS)
 
 export const DEFAULT_BLOSSOM_SERVERS = fromCsv(import.meta.env.VITE_DEFAULT_BLOSSOM_SERVERS)
 
+export const DEFAULT_SPACES = fromCsv(import.meta.env.VITE_DEFAULT_SPACES).map(normalizeRelayUrl)
+
 export const DEFAULT_PUBKEYS = import.meta.env.VITE_DEFAULT_PUBKEYS
 
 export const DUFFLEPUD_URL = "https://dufflepud.onrender.com"
diff --git a/src/app/groups.ts b/src/app/groups.ts
index 6eb441de..8ef0ec21 100644
--- a/src/app/groups.ts
+++ b/src/app/groups.ts
@@ -311,7 +311,7 @@ export const removeSpace = async (url: string) => {
   return publishThunk({event, relays})
 }
 
-export const setSpaceOrder = async (urls: string[]) => {
+export const setSpaces = async (urls: string[]) => {
   const list = get(userGroupList) || makeList({kind: ROOMS})
   const orderedUrls = uniq(urls.map(normalizeRelayUrl))
   const relayTags = list.publicTags.filter(t => t[0] === "r")
diff --git a/src/routes/spaces/+page.svelte b/src/routes/spaces/+page.svelte
index 0ccba90f..eb748ff7 100644
--- a/src/routes/spaces/+page.svelte
+++ b/src/routes/spaces/+page.svelte
@@ -26,7 +26,7 @@
   import SpaceAdd from "@app/components/SpaceAdd.svelte"
   import SpaceInviteAccept from "@app/components/SpaceInviteAccept.svelte"
   import SpaceJoin from "@app/components/SpaceJoin.svelte"
-  import {userSpaceUrls, loadUserGroupList, groupListPubkeysByUrl, setSpaceOrder} from "@app/groups"
+  import {userSpaceUrls, loadUserGroupList, groupListPubkeysByUrl, setSpaces} from "@app/groups"
   import {PLATFORM_RELAYS, DEFAULT_RELAYS} from "@app/env"
   import {bootstrapPubkeys} from "@app/social"
   import {parseInviteLink} from "@app/invites"
@@ -128,7 +128,7 @@
     lastDragTarget = undefined
 
     if (dragStartOrder && !isSameOrder(dragStartOrder, orderedSpaceUrls)) {
-      void setSpaceOrder(orderedSpaceUrls).catch(console.error)
+      void setSpaces(orderedSpaceUrls).catch(console.error)
     }
 
     dragStartOrder = undefined