---
id: trustme
version: "1.2.1"
license: MIT OR Apache-2.0
license_treatment: permissive
maintenance: active
---

# trustme — #1 quality TLS certs while you wait, for the discerning tester

License: permissive · Maintenance: active · Downloads: 1.1M/mo

## What it is and what it does

trustme is a lightweight Python package that creates fake certificate authorities and issues TLS certificates signed by them, specifically for testing network code. Instead of disabling certificate validation in tests (which masks production bugs), you use trustme to generate realistic test certificates that your test suite can trust, letting you validate the full TLS handshake without real certificates.

The package works both programmatically (creating CA and cert objects in Python) and from the command line (generating PEM files for use in non-Python test suites). It depends on cryptography for the underlying certificate operations and idna for domain name handling. The generated certificates are real certificates, just signed by your test CA rather than a trusted root authority.

Use it for:

- Test a Python web client or server that makes HTTPS connections without disabling certificate validation.
- Generate test certificates for use in non-Python test suites (e.g., shell scripts, Docker containers) via command-line or PEM files.
- Validate that your application correctly handles certificate chains and trust validation logic.
- Create temporary certificate files for libraries that require cert paths rather than SSL context objects.
- Test TLS error handling by issuing certs for different hostnames than the server is configured for.

## Worth the install?

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

trustme generates fake TLS certificates and certificate authorities for testing network code without needing real certificates or disabling certificate validation in tests.

Yes. trustme is a focused, well-maintained tool for a common testing need: validating TLS code without real certificates. Low install friction, permissive license, no known vulnerabilities, and active maintenance make it a safe choice for test suites. Install it if you test any code that makes HTTPS connections.

## Install

pip install trustme
uv add trustme
poetry add trustme

## Installing trustme

Before you install: Low install friction: pure Python wheel with only two runtime dependencies (cryptography and idna). Actively maintained with a recent release on 2025-01-02 and ongoing repository activity.

License in practice: Dual-licensed under MIT or Apache 2.0 (your choice), both permissive. You can use this freely in commercial or proprietary projects with minimal restrictions.

Quickstart:

pip install trustme

import trustme

ca = trustme.CA()
server_cert = ca.issue_cert("test-host.example.org")
ca.configure_trust(ssl_context)
server_cert.configure_cert(ssl_context)

Requires Python 3.9 or later.

Verify before relying:

- Whether the package works with both standard library ssl and PyOpenSSL contexts as claimed in the description.
- Performance characteristics when generating many certificates in a single test suite.
- Exact certificate format and standards compliance of generated certificates.

## Package facts

- License: MIT OR Apache-2.0 (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 1.1M/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

test TLS certificates, fake CA for testing, self-signed cert generation, testing HTTPS connections, mock certificate authority, test SSL certificates, TLS testing utilities, tls-testing, certificate-generation, test-doubles

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