Prove that a document existed before a specific moment in time. No subscription. No account. No server to trust. The proof lives in a .ots file and in the Bitcoin blockchain — and stays valid forever, even if OTSkit disappears tomorrow.

OpenTimestamps is an open standard for decentralized timestamp proofs. When you stamp a file, its cryptographic hash is submitted to public calendar servers that batch-anchor it into a Bitcoin block. The result is a compact .ots proof file you keep locally — no trusted third party required to verify it, ever.

Most existing OpenTimestamps tools are either abandoned, Python-only, or lack the resilience needed for production pipelines. OTSkit is a TypeScript-native implementation built for real-world use: circuit breakers, local SQLite persistence, automatic upgrade scheduling, and an MCP server so any AI agent can stamp files from a conversation.

If OTSkit disappears tomorrow, every proof ever generated stays valid forever.

AI agent audit trail — Every document your agent processes gets a tamper-proof timestamp. Prove what your agent did, on what file, and when.

File integrity — Stamp contracts, reports, or source code. Verify later that nothing changed.

Software releases — Timestamp each build artifact or SBOM. Prove your release existed before a specific date.

Digital preservation — Generate OAIS/PREMIS-compliant preservation packages anchored to Bitcoin.

The low-level protocol engine. A zero-dependency, pure TypeScript implementation of the OpenTimestamps protocol — create, serialize, deserialize, merge, and verify timestamp proofs with no npm supply chain risk. Supports Merkle tree batching so thousands of documents can be anchored in a single Bitcoin transaction. Built with TypeScript 6 strict mode and a fail-closed security posture that rejects any malformed input by default.

The production SDK. Wraps the full stamp → upgrade → verify workflow with enterprise-grade resilience: per-calendar circuit breakers, exponential backoff with jitter, dual timeouts, and configurable N-of-M submission thresholds so one failing calendar never blocks the rest. Requires Node.js 20+ (uses native crypto, dns, and net APIs). Tree-shakeable dual ESM/CJS build with @otskit/core as its only runtime dependency.

An MCP server exposing 8 timestamping tools to any MCP-compatible AI agent — Claude, Codex, or any agent that speaks the Model Context Protocol. Stores all proofs in a local SQLite database, runs an automatic upgrade scheduler to detect Bitcoin confirmations, and includes a CLI for direct use outside of agents. Setup is a single command.

Agent skills for producing standards-compliant digital preservation packages. Say "preserve this folder" and your agent generates a BagIt (RFC 8493) archive with OAIS/PREMIS metadata, computes its hash, and anchors it to Bitcoin — delivering four portable files: a .zip, a .sha256, a .ots proof, and a stamp ID for future verification.

New to MCP? → 5-minute setup guide

npm install -g @otskit/mcp
ots-mcp setup claude-code   # or: claude, codex

Restart your agent and ask: "Stamp this file and prove it exists on Bitcoin."

import { OpenTimestampsClient } from '@otskit/client';
import { createHash } from 'node:crypto';
import { readFileSync } from 'node:fs';

const hash = createHash('sha256').update(readFileSync('document.pdf')).digest('hex');
const client = new OpenTimestampsClient();
const proof = await client.stamp(hash); // Returns .ots proof as Buffer

// Later — upgrade when Bitcoin has confirmed (~60 min)
const upgraded = await client.upgrade(proof);

The closest alternatives are OriginStamp (commercial, proprietary proof format), the OpenTimestamps CLI (Python, no TypeScript SDK), and getAlby/ots-mcp (MCP-only, no local persistence):

OTSkit proves that a specific file existed before a specific Bitcoin block. That's the guarantee, and it's a strong one.

It does not prove:

• Who created the file
• That the file hasn't changed since
• Anything about legal validity in any jurisdiction

The proof is cryptographic, not legal. What it means in a legal context depends on your jurisdiction and circumstances. Consult a lawyer for use in legal proceedings.

MIT License · Built on the OpenTimestamps open standard