llms.txt

Introduction

Snaps are simple, nimble apps embedded in Farcaster casts. They render in the feed and respond to user input — buttons, sliders, text — without executing any code on the client. A snap server returns JSON; the Farcaster client displays it.

Beta: This is all still in beta and may change significantly over the next few weeks or months.

Using Claude Code? Tell your agent to

use https://docs.farcaster.xyz/snap/SKILL.md to build me an app that

Learn

  • Building a Snap — Ways to create a snap, from AI-assisted generation to manual implementation with the template.
  • Integrating Snaps — How to serve snap JSON alongside your normal site using content negotiation on the Accept header.
  • Persistent State — The key-value store available on every snap handler invocation for persisting state between requests.
  • Examples — Sample snap response payloads showing common UI patterns.

Reference

  • Spec — The full HTTP protocol: content negotiation, request/response lifecycle, versioning, and validation rules.
  • HTTP Headers — Accept, Content-Type, Vary, and Link for snap responses and fallbacks.
  • Elements — All 16 components: display, data, container, and field types.
  • Buttons — The button component, variants, layout, and how POST payloads are constructed when a user taps.
  • Actions — The 9 action types and their params.
  • Effects — Page-level overlays (confetti, etc.) that fire on render.
  • Constraints — Per-component validation limits and URL rules.
  • Theme & Styling — How accent colors work and why snaps specify only a palette name rather than hex values.
  • Color Palette — The named palette colors available for accent, progress bars, and bar charts.
  • Authentication — How POST requests are authenticated with JSON Farcaster Signatures (JFS) and how servers verify them.

Agents

  • Agents — Machine-readable docs, the skill file, and starting points for AI tools building or integrating snaps.

Contributing