cryptgeon is a secure, open source note and file sharing service inspired by PrivNote, written in Rust and Svelte, for anyone who wants to send self-destructing secrets without trusting the server with the plaintext.

What it is

cryptgeon is a sharing service consisting of a server, a web page and a CLI client, living in the file-sharing and private-notes space alongside services like PrivNote. Each note receives a generated 256-bit id and a 256-bit key; the id is used to save and retrieve the note, while the note itself is encrypted with XChaCha20-Poly1305 in the browser before it is ever sent to the server. Data is stored in memory and never persisted to disk, and because the server never receives the key, it cannot decrypt the contents even if it wanted to.

The concrete problem it solves is passing a credential, a document or a message to one recipient without leaving a durable, readable copy on any machine. Traditional sharing tools either store plaintext or ciphertext they can unlock; cryptgeon removes that exposure by keeping the key in the link and enforcing view counts and expirations on notes that only ever exist in RAM.

What it does

• Sends both text notes and files, with file uploads toggleable by the operator through ALLOW_FILES.
• Encrypts content client-side with XChaCha20-Poly1305 so the server only ever sees a msgpack payload plus ciphertext.
• Enforces view limits and time limits, configurable up to MAX_VIEWS (default 100) and MAX_EXPIRATION (default 360 minutes).
• Keeps every note in memory only, never writing it to disk, so notes disappear when the instance restarts or memory is reclaimed.
• Ships a CLI client, used as npx cryptgeon send text "This is a secret note", alongside the web interface.
• Supports rebranding through theme variables such as THEME_IMAGE, THEME_TEXT, THEME_PAGE_TITLE, THEME_FAVICON and IMPRINT_HTML.
• Offers an official Raycast extension for sending notes from the desktop launcher.

Who uses it and how

• Self-hosters who run the server against a Redis or Valkey cache, pointing CACHE at redis://cache/ and tuning SIZE_LIMIT (up to 512 MiB), ID_LENGTH and CACHE_PREFIX for their environment.
• Operators who want strict one-time notes and set ALLOW_ADVANCED to false, which forces every note to a single view.
• Teams that disable file sharing entirely with ALLOW_FILES=false and keep the service as a text-only secret channel.
• Command-line users who send secrets through the npx cryptgeon CLI without opening a browser, and Raycast users who trigger the same flow from a launcher extension.
• Deployers who serve multiple cryptgeon instances from one cache, accepting the documented race condition where a note may exceed its view count.

Getting started

The README documents the CLI as npx cryptgeon send text "This is a secret note", with further usage in packages/cli/README.md, and the hosted demo at cryptgeon.org; server deployment is configured entirely through the environment variable table above, and https is required.

How it compares

cryptgeon stands alongside PrivNote, the closed service that inspired it, as a self-hostable option under an MIT licence where the operator controls the deployment, the size limits and the theme. Because notes are encrypted in the browser and held only in the instance's memory, the data stays on infrastructure the operator owns rather than on a third party's.

When to use it — and when not

A self-hoster must run the server with an available Redis or Valkey cache and terminate TLS, and should remember that notes live in memory, so a restart or memory pressure evicts them — this is not a place to keep anything you need later. It is a poor fit for people who need durable history, for deployments requiring strict view counts across several instances, or for anyone uncomfortable operating a cache-backed service; note too that the README warns explicitly that view-count guarantees hold only with a single running instance.

npx cryptgeon send text "This is a secret note"

# docker-compose.yml

services:
  cache:
    image: valkey/valkey:7-alpine
    # This is required to stay in RAM only.
    command: valkey-server --save "" --appendonly no
    # Set a size limit. See link below on how to customise.
    # https://valkey.io/docs/latest/operate/rs/databases/memory-performance/eviction-policy/
    # --maxmemory 1gb --maxmemory-policy allkeys-lrulpine
    # This prevents the creation of an anonymous volume.
    tmpfs:
      - /data

  app:
    image: cupcakearmy/cryptgeon:v3
    depends_on:
      - cache
    environment:
      # Size limit for a single note.
      SIZE_LIMIT: 4 MiB
    ports:
      - 80:8000

    # Optional health checks
    # healthcheck:
    #   test: ["CMD", "curl", "--fail", "http://127.0.0.1:8000/healthz"]
    #   interval: 1m
    #   timeout: 3s
    #   retries: 2
    #   start_period: 5s