Small. Sloccount counts under 2000 lines of code, small enough to allow audits. The binaries can be under 50KB, small enough for many embedded targets.
Easy to deploy. Just add monocypher.c and monocypher.h to your project. They compile as C99 or C++ and are dedicated to the public domain (CC0-1.0, alternatively 2-clause BSD).
Portable. There are no dependencies, not even on libc.
Honest. The API is small, consistent, and cannot fail on correct input.
Direct. The abstractions are minimal. A developer with experience in applied cryptography can be productive in minutes.
Fast. The primitives are fast to begin with, and performance wasn't needlessly sacrificed. Monocypher holds up pretty well against Libsodium, despite being closer in size to TweetNaCl. (More detailed benchmark)

cppcryptfs is based on the design of gocryptfs, an encrypted overlay filesystem written in Go.

cppcryptfs is an implementation of the gocryptfs filesystem in C++ for Windows. cppcryptfs is compatible with gocryptfs. Filesystems created with one can generally be mounted (and synced) with the other.

Found on https://infosec-handbook.eu/recommendations/ via https://nuetzlich.net/gocryptfs/

Blog about cryptography, hash functions and more

ISA-L is a collection of optimized low-level functions targeting storage applications. ISA-L includes:
   Erasure codes - Fast block Reed-Solomon type erasure codes for any encode/decode matrix in GF(2^8).
   CRC - Fast implementations of cyclic redundancy check. Six different polynomials supported.
       iscsi32, ieee32, t10dif, ecma64, iso64, jones64.
   Raid - calculate and operate on XOR and P+Q parity found in common RAID implementations.
   Compression - Fast deflate-compatible data compression.
   De-compression - Fast inflate-compatible data compression.
BSD 3-Clause "New" or "Revised" License.
According to https://github.com/catid/cm256, ISA-L uses a O(N^3) Gaussian elimination solver for decoding. The CM256 decoder solves the linear system using a fast O(N^2) LDU-decomposition algorithm from "Pivoting and Backward Stability of Fast Algorithms for Solving Cauchy Linear Equations" (T. Boros, T. Kailath, V. Olshevsky), which was hand-optimized for memory accesses.
See also https://github.com/catid/leopard for a fast O(N log(N)) RS erasure decoder.

This package provides a library and a command-line tool named wormhole, which makes it possible to get arbitrary-sized files and directories (or short pieces of text) from one computer to another. The two endpoints are identified by using identical “wormhole codes”: in general, the sending machine generates and displays the code, which must then be typed into the receiving machine.

The codes are short and human-pronounceable, using a phonetically-distinct wordlist. The receiving side offers tab-completion on the codewords, so usually only a few characters must be typed. Wormhole codes are single-use and do not need to be memorized.

Code is at
https://github.com/larsmagne/eval-server.el

Yet another password manager.

CryptPad is a private-by-design alternative to popular office tools and cloud services. All the content stored on CryptPad is encrypted before being sent, which means nobody can access your data unless you give them the keys (not even us).

Noise is a framework for crypto protocols based on Diffie-Hellman key agreement. Noise can describe protocols that consist of a single message as well as interactive protocols.
Used in WireGuard https://www.wireguard.com/

AONT = All Or Nothing Transforms = a secure way to transmit a document to a recipient in such a way that the recipient either gets the entire unmolested document in originally submitted form, or nothing at all. This idea goes back to Ronald Rivest of MIT. Very clever idea. It is crypto without being crypto in a legal sense.