OpenAPI Guide

HTTPX provides automatic OpenAPI 3.1.0 specification generation, route documentation, schema reflection, and built-in interactive documentation UIs (Swagger UI, ReDoc, Scalar).

Overview

Define metadata alongside your routes. HTTPX aggregates all routes, parameters, request bodies, and responses into a single canonical OpenAPI specification.

const std = @import("std");
const httpx = @import("httpx");

pub fn main() !void {
    var gpa: std.heap.DebugAllocator(.{}) = .init;
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();
    const io = std.Io.Threaded.global_single_threaded.io();

    var server = try httpx.Server.init(allocator, io, .{
        .port = 8080,
        .enableDocs = true,
        .docs = .{
            .title = "Users API",
            .version = "1.0.0",
            .description = "Production API built with HTTPX",
        },
    });
    defer server.deinit();

    server.run();

Documentation UIs

• Swagger UI (/docs): Interactive API explorer with "Try It Out" request execution.
• ReDoc (/redoc): Three-panel responsive documentation focused on readability and schemas.
• Scalar (/scalar): Modern, sleek API reference with dark mode and client code snippets.

All three UIs consume the exact same canonical /openapi.json definition generated by HTTPX.

Related

• Web: OpenAPI
• Web: Documentation UIs
• Example: OpenAPI Server