utls
A fork of Go's standard TLS library that gives low-level control over the TLS ClientHello. It is used to make connections look like other clients, mainly for censorship circumvention.
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Share on XLicense: BSD-3-Clause
Overview
uTLS is a fork of Go's crypto/tls library that gives low-level access to the TLS ClientHello. The handshake itself is still done by crypto/tls, and uTLS only changes the ClientHello and exposes its details. Go's default ClientHello has a distinctive fingerprint, so tools can be easily recognised and blocked. With uTLS a program can imitate other clients, which is mainly used for anti-censorship. It requires Go 1.21 or newer.
Key features
- Read and write access to all bits of the ClientHello
- Fingerprint resistance, including randomized fingerprints
- Read access to ClientHandshakeState such as ServerHello
- Support for fake session tickets
Best for
Aimed at Go developers building anti-censorship or similar tools that must not stand out. The README warns parts of its documentation may be outdated, so check godoc.
- Upstream
- refraction-networking/utls
- Fork on GitHub
- Guo-astro/utls
- Upstream stars
- 2.6k
- Category
- Security and networking
- Language
- Go
- License
- BSD-3-Clause
- Forked
- 2025-10-15
- Sync status
- Updated by last syncLast synced 2026-11-09
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