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S2n Alternatives
Similar projects and alternatives to s2n
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SaaSHub
SaaSHub - Software Alternatives and Reviews. SaaSHub helps you find the best software and product alternatives
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wolfssl
The wolfSSL library is a small, fast, portable implementation of TLS/SSL for embedded devices to the cloud. wolfSSL supports up to TLS 1.3 and DTLS 1.3! Update to wolfSSL 5.9.1 for the latest CVE fixes.
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mbedTLS
An open source, portable, easy to use, readable and flexible TLS library, and reference implementation of the PSA Cryptography API. Releases are on a varying cadence, typically around 3 - 6 months between releases.
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aws-lc
AWS-LC is a general-purpose cryptographic library maintained by the AWS Cryptography team for AWS and their customers. It Ñ–s based on code from the Google BoringSSL project and the OpenSSL project.
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LibreSSL
LibreSSL Portable itself. This includes the build scaffold and compatibility layer that builds portable LibreSSL from the OpenBSD source code. Pull requests or patches sent to tech@openbsd.org are welcome.
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NOTE:
The number of mentions on this list indicates mentions on common posts plus user suggested alternatives.
Hence, a higher number means a better s2n alternative or higher similarity.
s2n discussion
s2n reviews and mentions
Posts with mentions or reviews of s2n.
We have used some of these posts to build our list of alternatives
and similar projects. The last one was on 2026-01-27.
- AI found 12 vulnerabilities in OpenSSL
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Why SSL was renamed to TLS in late 90s (2014)
Then there was Amazon: https://github.com/aws/s2n-tls
I had high hopes for s2n, but looks like it never really caught on outside of AWS.
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OpenSSL bug exposed up to 255 bytes of server heap and existed since 2011
I started writing s2n the day after Heartbleed and the first lines of code were for the stuffer interface. A stuffer is a buffer for stuff, and it's like Java buffered I/O for C. You can get a flavor from reading the header: https://github.com/aws/s2n-tls/blob/main/stuffer/s2n_stuffer...
The implementation is incredibly simple. Treat all blocks of memory as blob with a known size and then read/write into those blobs with a cursor to track progress and bounds checks on every access. Fence all serialization/deserialization through a safe low level interface. Not only do you get memory safety (which we later proved using formal reasoning) ... but when you're parsing message formats it lends itself to a declarative coding style that makes it very clear what the structure is. You can also do lifecycle things, like erasing sensitive memory with zeroes when you're done with it, making sure things don't show up in core dumps, etc. BoringSSL introduced a Crypto_bytes API that also did some of this plus bounds checking, and retrofit it into OpenSSL.
OpenSSL on the other hand is a horrific mash up of raw pointer arithmetic, ad-hoc parsers interleaved with business logic and control flow. I could never keep it straight, and it always scared me to review.
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S2n-TLS – A C99 implementation of the TLS/SSL protocol
It seems to support multiple options but requires you pick at least one of them. https://github.com/aws/s2n-tls/blob/main/docs/BUILD.md#build...
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OpenSSL 1.1.1 End of Life
I think GnuTLS is probably the second most popular TLS library, after openssl.
I'll also mentions s2n and rustls-ffi for completeness as C libraries, though the former isn't widely used, and the latter is very experimental still. https://github.com/aws/s2n-tls and https://github.com/rustls/rustls-ffi respectively.
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I want XAES-256-GCM/11
I've seen operating on unauthenticated plaintext enough times to list it as my own pet peeve with AES-GCM. But it's a problem for chunked messages too. A few years ago we released a SCRAM mode that makes very minimal changes to AES-GCM so that it mathematically can't operate on unauthenticated plaintext. https://github.com/aws/s2n-tls/tree/main/scram
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Golang is evil on shitty networks
> The documentation is kind of vague, but apparently you have to re-enable it regularly.[3]
This is correct. And in the end it means more or less that setting the socket option is more of a way of sending an explicit ACK from userspace than a real setting.
It's not great for common use-cases, because making userspace care about ACKs will obviously degrade efficiency (more syscalls).
However it can make sense for some use-cases. E.g. I saw the s2n TLS library using QUICKACK to avoid the TLS handshake being stuck [1]. Maybe also worthwhile to be set in some specific RPC scenarios where the server might not immediately send a response on receiving the request, and where the client could send additional frames (e.g. gRPC client side streaming, or in pipelined HTTP requests if the server would really process those in parallel and not just let them sit in socket buffers).
[1] https://github.com/aws/s2n-tls/blob/46c47a71e637cabc312ce843...
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S2n-QUIC (Rust implementation of QUIC)
It looks like by default s2n-quic uses this TLS implementation, which is not based on the ring crate (though it is written in C)
https://github.com/aws/s2n-tls
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LibreSSL Languishes on Linux
I would be interested in the other SSL implementations:
- https://github.com/awslabs/s2n
- https://boringssl.googlesource.com/boringssl
- https://bearssl.org/
Are these subpar implementations or there are other reasons not to use these?
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A note from our sponsor - SaaSHub
www.saashub.com | 22 Jul 2026
Stats
Basic s2n repo stats
12
4,743
9.5
5 days ago
awslabs/s2n is an open source project licensed under Apache License 2.0 which is an OSI approved license.
The primary programming language of s2n is C.
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