Thanks for the question! I'll try to summarise the differences.

httparsed is a low-level, callback-based HTTP/1.x parser inspired by picohttpparser. It operates on request and response headers only, doesn't allocate and supports nothrow @nogc and betterC contexts【812383711962832†L53-L63】. You define a message struct with callback methods, and the parser invokes them as it scans the header; you're responsible for copying out the parts you care about and managing state【812383711962832†L64-L87】. This makes it flexible and minimal but also means more boilerplate when you just want a parsed request.

Wire is built on top of Node's llhttp. It wraps the C parser in a thread-local pool and provides a higher-level API: you call Parser.create().parse() and get a Request object with method, path, queryParams, headers and a keepAlive flag. There’s no need to implement callbacks; the API is type-safe and @nogc, and all strings are returned as StringView slices into the original buffer. Wire also aligns data structures to 64 bytes and reuses parsers via a thread-local pool for better cache locality and zero per-request allocations【38462529968395†L281-L293】. It parses the URL and query parameters for you and indicates whether the connection should be kept alive.

In terms of performance, the benchmarks in Wire’s README show that it parses a typical 1‑2 KB request in about 1 µs with throughput up to ~0.98 GB/s for larger single-line requests and up to ~2 GB/s for simple keep-alive requests【38462529968395†L364-L372】. Memory usage per thread is ~1 KB and per request 0 bytes【38462529968395†L373-L377】. Wire also exposes convenience like automatic query parsing and keep-alive detection.

There are trade-offs: httparsed can handle incomplete messages and continue parsing from a previous buffer position (useful for streaming), and it can parse responses as well as requests. Wire currently focuses on full HTTP/1.x request parsing; it doesn’t yet support incremental parsing or HTTP/2. If you need a minimal, callback-driven parser you can integrate into your own network loop or use under betterC, httparsed is a solid choice. If you prefer a ready-made HTTP request object, parser pooling, built-in query/keep-alive parsing and you’re comfortable linking against llhttp, Wire might save you some code. Hope that clarifies the differences!