Deser revisits Rust serialization by giving the format control

Armin Ronacher has revived Deser, a Rust serialization experiment that reverses Serde’s control flow. Formats push events into value handlers, while a driver keeps nested state on the heap instead of recursively consuming the call stack. This supports different buffering and error-handling choices, but deliberately excludes formats such as Protobuf that require external type information.

Armin Ronacher · Sep 29, 2026

Why it matters

Rust developers can examine a concrete trade-off between format flexibility and implementation architecture.

More context

Try one representative input through the documented crates and examples before considering migration. JSON, YAML, TOML and several other formats are implemented; compare error locations and deeply nested inputs as well as speed.

Keep in mind

This is a revived experiment, not a drop-in ecosystem replacement. It uses unsafe code internally and incurs dynamic-dispatch overhead. Performance varies by workload; 1min has not reproduced the author’s benchmarks.

Original read