11 releases (7 stable)

25.12.19 Dec 19, 2025
25.9.23 Sep 24, 2025
25.2.10 Feb 11, 2025
24.12.23 Dec 23, 2024
0.1.1 Jun 29, 2020

#1615 in Encoding

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42,056 downloads per month
Used in 78 crates (35 directly)

Apache-2.0

125KB
2.5K SLoC

Flexbuffers

Flexbuffers is a schema-less binary format developed at Google. FlexBuffers can be accessed without parsing, copying, or allocation. This is a huge win for efficiency, memory friendly-ness, and allows for unique use cases such as mmap-ing large amounts of free-form data.

FlexBuffers' design and implementation allows for a very compact encoding, with automatic sizing of containers to their smallest possible representation (8/16/32/64 bits). Many values and offsets can be encoded in just 8 bits.

FlexBuffers supports Serde for automatically serializing Rust data structures into its binary format.

See Examples for Usage:

Flexbuffers is the schema-less cousin of Flatbuffers.

Dependencies

~0.5–1.2MB
~26K SLoC