serde_bytes

serde_bytes is a small companion crate to Serde that gives &[u8] and Vec<u8> specialized, efficient serialization instead of the generic per-element treatment Serde applies to ordinary slices and vectors. Without it, Rust’s lack of specialization forces Serde to serialize a byte slice one element at a time, which is wasteful for binary formats that can represent contiguous bytes compactly.

The crate exposes serde_bytes::Bytes and serde_bytes::ByteBuf wrapper types, plus a #[serde(with = "serde_bytes")] field attribute so structs can opt into the optimized path without introducing a wrapper type at all. Maintained by dtolnay (the author of Serde itself), it is a no_std-compatible, near-zero-dependency crate widely used anywhere binary payloads move through Serde-based (de)serialization, such as bincode, MessagePack, or custom binary protocols.

What You Get

• serde_bytes::Bytes and serde_bytes::ByteBuf wrapper types for borrowed and owned byte data
• A #[serde(with = "serde_bytes")] field attribute to opt struct fields into optimized handling without a wrapper type
• no_std and no_std + alloc support via the std/alloc feature flags, keeping the crate usable in embedded and constrained environments
• Zero-cost integration with any Serde-compatible binary format (bincode, MessagePack, CBOR, etc.)

Common Use Cases

• Serializing binary payloads (file contents, hashes, raw network frames) efficiently with bincode or another Serde binary format
• Defining protocol structs where one or more fields are raw byte buffers that should not be encoded as generic sequences
• Building no_std embedded firmware that still needs compact Serde-based serialization of byte data
• Avoiding accidental O(n) per-byte serialization overhead in performance-sensitive data pipelines

Under The Hood

Architecture - The crate is intentionally minimal: bytes.rs and bytearray.rs define the Bytes/ByteBuf wrapper newtypes, while ser.rs and de.rs implement custom Serialize/Deserialize impls that call into serde_core’s serialize_bytes/deserialize_bytes hooks rather than the default sequence-serialization path, giving formats a chance to represent the data compactly. Tech Stack - Built directly against serde_core (the dependency-free core of Serde) with std/alloc feature flags controlling no_std compatibility, and zero runtime dependencies beyond that core. Code Quality - Despite its small size, the crate has a dedicated tests/ suite (test_derive.rs, test_partialeq.rs, test_serde.rs) exercising derive-macro interop, equality semantics, and round-trip serialization, plus dev-dependencies on bincode, serde_derive, and serde_test to validate real-world usage patterns. API Design - The API surface is deliberately tiny: two wrapper types plus one attribute string, requiring no boilerplate beyond #[serde(with = "serde_bytes")] on a field, which keeps the crate trivially adoptable in any existing Serde-derived struct.