Overview

Choose Fast TypeScript SDKs for native transactions, AllSet bridging, x402 HTTP payments, identity, and artifact attestations.

The Fast SDK monorepo is the source of truth for package APIs and runnable examples. The packages are independently versioned; use the published package README for the exact version you install.

Start with Choose your Fast tool for task-based recommendations, or AI agent documentation access for Markdown and MCP retrieval.

Package	Purpose
@fastxyz/sdk	Fast account queries, transaction construction, signing, and submission
@fastxyz/allset-sdk	Supported EVM ↔ Fast deposit, withdrawal, and intent workflows
@fastxyz/x402-client	Pay for x402-protected HTTP resources
@fastxyz/x402-server	Protect Express routes with x402 requirements
@fastxyz/x402-facilitator	Verify and settle supported x402 payments
@fastxyz/x402-types	Shared x402 protocol types
@fastxyz/schema	Fast schemas and codecs (the directory is fast-schema, but the npm name is @fastxyz/schema)
@fastxyz/cli	Interactive and scripted account, funding, send, and x402 commands

The same monorepo also publishes @fastxyz/fastid-sdk and @fastxyz/sign-sdk. Identity and signing have separate trust and recovery models; consult their linked references rather than treating them as payment helpers.

FastProvider is a REST client. Signer holds Ed25519 signing authority. TransactionBuilder constructs a transaction with an explicit network ID, signer, and nonce; the provider submits the signed envelope. AllSet cross-network operations are asynchronous and must be tracked on both sides. x402 adds HTTP payment negotiation above these network-specific operations.

For current funding routes, see Funding Abstraction. Planned integrations are not supported APIs until their package documentation says otherwise.