Secondlayer

The hosted indexer for Stacks. Curl decoded chain data keyless in ten seconds (Index), deploy a one-file TypeScript indexer and get hosted Postgres tables behind a public REST API (Subgraphs), or consume the raw signed event firehose + parquet dumps to build your own (Streams) — no node, no infra. Webhooks and an MCP server included. See STRATEGY.md.

curl "https://api.secondlayer.tools/v1/index/events?event_type=ft_transfer&limit=5"

• Hosted — managed platform, free during open beta. Reads are public; a key gates writes.
• Self-host — the whole stack is MIT-licensed. docker compose up runs indexer + API + processor on your own hardware.

Quickstart (hosted)

bun add -g @secondlayer/cli

sl login
sl project create my-app && sl project use my-app

# Index a contract into a typed, queryable Postgres table
sl subgraphs scaffold SP1234ABCD.my-contract -o subgraphs/my-contract.ts
sl subgraphs deploy subgraphs/my-contract.ts --start-block <recent-block>
sl subgraphs query my-contract <table> --sort _block_height --order desc

# Push new rows to a webhook
sl subscriptions create my-hook --runtime node \
  --subgraph my-contract --table <table> --url https://<host>/webhook

Subscriptions are polymorphic. The above is a subgraph subscription (fires on a subgraph table's rows). A chain subscription fires on raw chain events with no subgraph — a turnkey webhook on a contract, event, function, or trait — and is created via the SDK, REST, or MCP with a triggers array:

import { SecondLayer, trigger } from "@secondlayer/sdk";

const sl = new SecondLayer({ apiKey: "sk-sl_..." });
const { subscription, signingSecret } = await sl.subscriptions.create({
  name: "amm-swaps",
  url: "https://my-app.com/webhook",
  triggers: [trigger.contractCall({ contractId: "SP....amm", functionName: "swap-*" })],
});

Full walkthrough → QUICKSTART · commands → CLI reference.

Read it from anywhere

Reads are public for public subgraphs (managed deploys default public; private ones need the owner's sk-sl_ key); the SDK defaults to https://api.secondlayer.tools.

import { SecondLayer } from "@secondlayer/sdk";

const sl = new SecondLayer();
const { rows, next_cursor, tip } = await sl.subgraphs.rows("my-contract", "<table>", {
  order: "desc",
  limit: 25,
});

curl "https://api.secondlayer.tools/v1/subgraphs/my-contract/<table>?_limit=25"

Pages are _id-keyset: pass ?cursor=<next_cursor> to resume, _order=asc|desc for direction.

MCP — point any MCP client at bunx -p @secondlayer/mcp secondlayer-mcp (SECONDLAYER_API_URL=https://api.secondlayer.tools). Set SL_API_KEY to enable writes (deploy/manage). See MCP README.

Packages

Two TypeScript SDKs, one chooser: @secondlayer/sdk talks to the platform (query subgraphs, manage webhooks/keys); @secondlayer/stacks is low-level chain primitives (Clarity decoding, reads). Most apps only need sdk.

Package	Description
@secondlayer/cli	sl binary — auth, projects, subgraph deploy, Clarity code-gen
@secondlayer/sdk	TypeScript SDK — typed subgraph queries, webhooks
@secondlayer/mcp	MCP server — subgraphs + scaffolding for AI agents
@secondlayer/stacks	viem-style Stacks client — public/wallet, BNS, AI-SDK tools
@secondlayer/subgraphs	defineSubgraph() — declarative schema, triggers + handlers
@secondlayer/shared	Shared db, schemas, crypto helpers
@secondlayer/api	REST API — hosted + self-host modes

Self-host

git clone https://github.com/ryanwaits/secondlayer
cd secondlayer
cp docker/.env.example docker/.env   # fill in secrets
docker compose -f docker/docker-compose.yml up -d

OSS quickstart · operations & backups in docker/docs/.

Development

bun install && bun run build && bun run test

Releases flow through Changesets: bun run version to bump, bun run release to publish.

License

MIT