Flash

Spaced-repetition flashcards you study with your AI. Flash is a small self-hosted server: a web app for your decks and an MCP server that lets Claude, ChatGPT, Grok or any MCP client create cards from what you're learning, quiz you out loud, grade your answers and file the reviews with the FSRS scheduler. One Rust binary, one SQLite file, no accounts anywhere but yours.

The hosted version, with self-serve signup, Google/Apple sign-in and a community deck library, is at flashmemorize.com. iOS and Android apps are on the way and not out yet. This repository is the core it all runs on.

Today	Study	Connect your AI

_{Demo decks under the test persona; the conduction diagram is by Madhero88 via Wikimedia Commons, CC BY 3.0.}

Why not Anki + AnkiConnect?

AnkiConnect is a bridge into the desktop app: it only answers while Anki is open on that machine, and it speaks Anki's own JSON, not MCP. Flash is a server. It is reachable from your phone, from a Claude connector, from Claude Code in a terminal, all at once, and the scheduling lives in the server so every surface sees the same queue. It imports .apkg decks whole (cloze, hints, images, audio, LaTeX, typed answers, nested decks) and exports them back at any time, so trying it costs nothing.

Five-minute quickstart (Docker)

git clone https://github.com/flash-cards/flash && cd flash
cp .env.example .env            # set FLASH_BASE_URL to the URL you'll reach it at
docker compose up -d
docker compose logs flash | grep enroll

The first boot finds an empty database and logs a one-time link:

no users yet. Enroll the first admin within 24h at:
https://cards.example.com/enroll/<token>

Open it, add a passkey or a password, and you are the admin. Every later account is created from Settings → Invite: there is no public signup on a self-hosted Flash, by design.

Without Docker: cargo build --release -p flash-server, then run target/release/flash-server with the same environment variables. The binary embeds its templates and static assets; it writes under FLASH_DATA_DIR, plus short-lived scratch files for an import or export in the system temp directory (the systemd unit gives it a private one).

Upgrading

docker compose pull && docker compose up -d

Everything Flash writes lives in the flash-data volume (/data in the container: the SQLite database, media, voice clips), and the image holds nothing of yours, so a newer image finds your data where the old one left it. On its first boot a newer version brings the database schema forward before it listens, one step at a time, each in its own transaction; /healthz then reports the new version. Migrations only go forward: take a copy before an upgrade if you may want to return, and do not start an older image on a volume a newer one has opened. A consistent copy is the volume with the container stopped:

docker compose stop flash
docker run --rm -v flash-data:/data -v "$PWD":/backup debian:bookworm-slim \
    tar czf /backup/flash-data.tgz -C /data .
docker compose start flash

latest follows every release. ghcr.io/flash-cards/flash:0.3 takes patch releases only and :0.3.0 never moves; pin one of those in docker-compose.yml if you would rather choose when to move. What each version changed is in CHANGELOG.md, and a release that changes the MCP tools says so there: refresh the connector's tool definitions in each AI client after that upgrade. Without Docker the same holds for FLASH_DATA_DIR: keep the directory, replace the binary, start it.

Connecting your AI

Flash serves MCP at /mcp (Streamable HTTP) with OAuth 2.1: the client registers itself, sends you to Flash's login page, and gets a token scoped to your account.

• Claude.ai / Claude mobile: Settings → Connectors → Add custom connector → paste https://<your host>/mcp. Claude's connectors need a publicly reachable HTTPS origin, so put Flash behind a reverse proxy with a certificate, such as Caddy:
  Caddyfile

  Copy

  cards.example.com {
      reverse_proxy 127.0.0.1:8437 {
          header_up X-Real-IP {remote_host}
      }
  }
  

  and set FLASH_CLIENT_IP_HEADER=x-real-ip so the rate limiters see each visitor rather than the proxy (see the note under Configuration). A tunnel (Cloudflare Tunnel, Tailscale Funnel, ngrok) works the same way if you'd rather not open a port.
• Claude Code: claude mcp add --transport http flash https://<your host>/mcp. Claude Code and Claude Desktop run on your own machine, so a LAN address works for the MCP connection as long as FLASH_BASE_URL matches what you paste. The web UI itself needs HTTPS or http://localhost: its session cookie is marked Secure, and a browser drops it over plain http to any other host (the server says so at boot).
• ChatGPT (Plus and up, Developer mode): Settings → Apps → add the same URL as an MCP server. Grok: Connectors → New → Custom.

Once connected, say "quiz me on my pharmacology deck" and follow along. The web app at / is where you import decks, edit cards and read your stats. What the tools take and return, for anyone building a client, is in the MCP contract.

Configuration

Everything is an environment variable; the core needs only the first three. Optional groups are all-or-nothing: a partial set is a boot error, an absent set turns the feature off.