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cpp-httplib

cpp-httplib is a single-header HTTP library for C++. It is designed for convenience, not for building large-scale service ecosystems.

In Kumo, it is used for quick validation, local tools, and lightweight services.

1. What cpp-httplib actually is​

cpp-httplib is:

  • Header-only
  • Zero build system
  • Zero runtime dependencies
  • Very small API surface
  • Easy to embed into any C++ project

It gives you:

  • HTTP server
  • HTTP client
  • Basic TLS support
  • Routing
  • Request and response handling

You include one header and you are done.

That is its entire value.

2. What it is not​

cpp-httplib does not provide:

  • Service discovery
  • Load balancing
  • Connection pooling
  • Deadlines or cancellation
  • Streaming
  • Backpressure
  • Structured metadata
  • Authentication frameworks
  • Observability integration
  • Cross-language support
  • A production RPC ecosystem

It is not a service platform. It is a utility HTTP stack.

3. Where it fits​

cpp-httplib fits in exactly these scenarios:

  • Local development servers
  • Debug endpoints
  • Internal admin APIs
  • One-off tools
  • Data import/export utilities
  • Temporary validation services
  • Test harnesses

These are places where:

  • You want to start something in minutes
  • You do not want to deal with toolchains
  • You do not want to manage runtime dependencies
  • You do not need a large ecosystem

4. Why it is not used for core services​

In real production systems, HTTP endpoints quickly require:

  • Authentication
  • Authorization
  • Rate limiting
  • Tracing
  • Metrics
  • TLS management
  • Multi-language clients
  • Deployment automation

cpp-httplib does not integrate with any of this.

If you try to build a real service on top of it, you will end up re-implementing half of an RPC stack.

That is exactly what gRPC and brpc already solve.

5. Typical usage pattern​

cpp-httplib is ideal for:

  • "Give me a quick HTTP endpoint so I can test this"
  • "Expose a debug API"
  • "Serve a small control or admin interface"
  • "Validate data flow before building the real service"

It is a prototype and tooling library, not a service platform.

6. Minimal example​

#include "httplib.h"

int main() {
    httplib::Server svr;

    svr.Get("/ping", [](const httplib::Request&, httplib::Response& res) {
        res.set_content("pong", "text/plain");
    });

    svr.listen("0.0.0.0", 8080);
}

This is exactly what cpp-httplib is good at: a working HTTP service in a few lines of code.

7. Summary​

cpp-httplib is chosen when:

  • You need something now
  • You want minimal friction
  • You do not need an ecosystem
  • You do not want operational complexity

It is not used for:

  • Business APIs
  • High-QPS services
  • Multi-language integration
  • Long-term service infrastructure

In Kumo, cpp-httplib is a tool, not a platform.