yolow64: a Base64 codec for Rust that outruns the incumbents — extracted from PageSift

A developer has released yolow64, an MIT-licensed Base64 codec for Rust extracted from the PageSift web-content engine, featuring runtime-dispatched SIMD (AVX2 with an assembly bulk decode loop on Linux x86-64, NEON on AArch64, and a scalar fallback) with zero runtime dependencies. Benchmarked on an i7-10700, the library reports roughly 6.5–9× faster strict-mode encode and decode than the base64 crate and 1.7–2.5× faster than base64-simd at 4 KiB–4 MiB, with CRLF-tolerant decode about 4× faster than base64-simd's forgiving_decode. The author notes that at inputs of 128 bytes or less the libraries trade wins within noise.

While building PageSift a Rust web-content engine for LLM pipelines , I kept hitting Base64 in places where throughput and allocation control actually matter: browser screenshots, MCP resources, proxy authentication. The codec that grew inside PageSift is now its own MIT-licensed library: yolow64 . - Runtime-dispatched SIMD: AVX2 with an assembly bulk decode loop on Linux x86-64 , NEON on AArch64, scalar fallback; runtime detection is cached. - Zero runtime dependencies, std only, Rust 1.89+. - Slice / append / owned-output APIs, validation without decoding, streaming decode, and a one-shot data-URL builder. - Whitespace-tolerant mode ignores exactly space/tab/CR/LF in a single pass — built for MIME-style input. Measured on an i7-10700 same process, three full runs, medians of seven-round medians; full method, charts and raw CSVs in the repo : - Strict mode at 4 KiB–4 MiB: ~6.5–9× faster than the base64 crate, ~1.7–2.5× faster than base64-simd , encode and decode. - CRLF-tolerant decode: ~4× faster than base64-simd's forgiving decode at the same sizes. - On the same machine it runs level with moego, the fastest Go implementation I measured. - Honest footnote: at ≤128 B inputs the three libraries trade wins — those differences are nanoseconds and noise-sensitive, and the repo's tables print them as-is. The whitespace modes also don't accept exactly the same inputs across libraries; the comparison covers valid padded CRLF inputs. Repo: https://github.com/YOLOW92/yolow64 https://github.com/YOLOW92/yolow64 — benchmarks are reproducible from the included harness; corrections welcome.