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Requirements

  • Bun ≥ 1.0 (runs TypeScript functions + codegen)
  • Rust ≥ 1.85 (required to build the CLI from source — edition 2024)
  • Node.js ≥ 18 (optional, for client tooling)

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Install the CLI

Pylon is currently installed from source. A one-line install script and Homebrew tap are on the roadmap but not yet shipped. 
git clone https://github.com/pylonsync/pylon
cd pylon
cargo install --path crates/cli --locked
This compiles and places a pylon binary in ~/.cargo/bin/. Verify: 
pylon --version
pylon doctor
pylon doctor checks that bun, node, and the supporting tooling are available.

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Install Bun

Pylon uses Bun to run TypeScript server functions and to bundle the client code generator. If you don’t have it: 
curl -fsSL https://bun.sh/install | bash

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Client SDKs

Install into your web app: 
bun add @pylonsync/sdk @pylonsync/react

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Directory conventions

A Pylon app usually looks like this: 
my-app/
  app.ts                 # schema + policies + manifest
  functions/             # server functions (*.ts)
  client/                # your React components
  web/                   # Vite app (or Next.js, etc.)
    package.json
    vite.config.ts
    src/main.tsx
  package.json
  pylon.manifest.json    # generated
  pylon.client.ts        # generated
pylon dev app.ts watches app.ts + functions/ and regenerates pylon.manifest.json + pylon.client.ts on every change.

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Environment variables

VariableDefaultPurpose
PYLON_DB_PATH.pylon/dev.dbSQLite file location (ignored if DATABASE_URL is set)
DATABASE_URL(unset)postgres://... connection string. When set, Pylon uses the Postgres adapter instead of SQLite
PYLON_FILES_DIR.pylon/uploadsFile upload storage
PYLON_CORS_ORIGIN* (dev only)Allowed origin in prod
PYLON_DEV_MODEtrueDev-only behavior (generous rate limits, CORS *)
PYLON_PORT4321HTTP port
PYLON_RATE_LIMIT_MAX100Requests per window
PYLON_FN_RATE_LIMIT_MAX30Function calls per window
See Reference → CLI for the full list.