---
id: opentimestamps
version: "0.4.5"
license: LGPL3
license_treatment: copyleft
maintenance: aging
---

# opentimestamps — Create and verify OpenTimestamps proofs

License: copyleft · Maintenance: aging · Downloads: 175.4K/mo

## What it is and what it does

OpenTimestamps is a Python library for working with OpenTimestamps proofs—cryptographic structures that prove a piece of data existed at a specific point in time by anchoring it to the Bitcoin blockchain. The library splits its codebase into consensus-critical modules (opentimestamps.core.*) that define timestamp validation semantics, and application-level modules that build on them. You use it to create proofs that data was present at a given moment, and to verify those proofs later, with the guarantee that any change to the original data will invalidate the proof.

The package depends on pycryptodomex for cryptographic operations and python-bitcoinlib for blockchain interaction. It installs as a pure Python wheel with low friction. The project is in Beta status and has aged since its last release in January 2023, though the repository remains unarchived and receives occasional maintenance. No known security vulnerabilities are recorded.

Use it for:

- Prove that a document or file existed at a specific time without relying on a centralized timestamp authority
- Create immutable audit trails for compliance by anchoring records to the Bitcoin blockchain
- Verify the authenticity and temporal integrity of timestamped data in legal or regulatory contexts
- Build applications that need cryptographic proof of data existence without trusting a single server

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

A Python library for creating and verifying OpenTimestamps cryptographic proofs, which anchor data to the Bitcoin blockchain for tamper-evident timestamping.

Yes, with conditions. Install if you need Bitcoin-backed timestamping and can accept that the package is aging (last release over a year old). The low install friction, absence of known vulnerabilities, and active repository make it viable for production use. However, verify that the consensus-critical modules remain compatible with your target Bitcoin protocol version, and test thoroughly on your Python version before deploying. The LGPL3 copyleft license requires that any modifications be shared under the same terms.

## Install

pip install opentimestamps
uv add opentimestamps
poetry add opentimestamps

## Installing opentimestamps

Before you install: Low friction installation as a pure Python wheel. The package is aging (last release 2023-01-25, 1297 days old) but the repository remains active and unarchived with recent commits as of 2025-03-18. Maintenance signal is limited but not abandoned.

License in practice: Licensed under LGPL3 (copyleft). Any derivative or modified version must be released under the same license; static linking or bundling requires careful attention to license compliance obligations.

Quickstart:

pip install opentimestamps

import opentimestamps
# Create or verify OpenTimestamps proofs using the library's core API

Requires pycryptodomex and python-bitcoinlib as runtime dependencies; on some macOS setups, SSL root certificates may need to be installed separately.

Verify before relying:

- Whether the package's consensus-critical core modules (opentimestamps.core.*) remain compatible with current Bitcoin protocol versions
- Current test coverage and whether unit tests pass on modern Python 3.x versions
- SSL certificate handling on modern macOS versions (documentation mentions Python 3.7 workaround)

## Package facts

- License: LGPL3 (copyleft)
- Python support: unspecified
- Install friction: low
- Maintenance: aging
- Downloads: 175.4K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

opentimestamps proof creation, bitcoin timestamping library, cryptographic proof verification, blockchain timestamp anchoring, tamper-evident timestamping, opentimestamps python, timestamp validation bitcoin, blockchain, timestamping, bitcoin

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