How to set up HTTPS with cpp-httplib?

Define CPPHTTPLIB_OPENSSL_SUPPORT (or other TLS backends), include httplib.h, and use SSLServer with certificate and key files. The README provides examples for multiple TLS backends and custom verification callbacks.

Does cpp-httplib support asynchronous requests?

No, it uses a blocking I/O model. The README states clearly that if you need non-blocking socket I/O, this is not the library for you, making it unsuitable for async-heavy applications.

cpp-httplib vs Boost.Beast for HTTP in C++

cpp-httplib is simpler and header-only with built-in features like static serving, while Boost.Beast offers lower-level, asynchronous control but requires more boilerplate. Choose cpp-httplib for quick integration, Boost.Beast for high-performance customization.

How to handle file uploads in cpp-httplib?

Use the multipart form data handling: parse req.form for files and fields, sanitize filenames with httplib::sanitize_filename, and save content. The README includes a detailed example with code for validation and streaming.

Can cpp-httplib be used on Raspberry Pi or ARM devices?

Yes, for 64-bit ARM systems, as it's cross-platform. However, avoid 32-bit ARM due to the library's lack of support and potential security issues mentioned in the warnings.

What TLS backends are supported and what are their limitations?

Supports OpenSSL 3.0+, Mbed TLS 2.x/3.x, and wolfSSL 5.x. Mbed TLS and wolfSSL have limitations: get_ca_certs() only reflects certificates loaded via load_ca_cert_store(), not system certs.

How to compress responses with cpp-httplib?

Enable compression support via CPPHTTPLIB_ZLIB_SUPPORT for gzip, CPPHTTPLIB_BROTLI_SUPPORT, or CPPHTTPLIB_ZSTD_SUPPORT, then link the libraries. The server compresses compatible MIME types automatically, detailed in the Compression section.

Open-Awesome

Cpp-HttpLib

MITC++v0.54.1

A C++11 single-file header-only HTTP/HTTPS server and client library for building web services and clients.

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16.8k stars2.7k forks0 contributors

What is Cpp-HttpLib?

cpp-httplib is a C++11 header-only library that provides both HTTP server and client functionality in a single file. It enables developers to quickly embed web server capabilities into applications or create HTTP clients for consuming APIs, with built-in support for SSL/TLS, WebSocket, and static file serving.

Target Audience

C++ developers building embedded web services, local APIs, IoT applications, or lightweight HTTP clients who prefer a simple, dependency-minimal solution over larger frameworks.

Value Proposition

Developers choose cpp-httplib for its zero-configuration integration, comprehensive feature set including SSL and real-time protocols, and the convenience of a single-header library that works across platforms without complex build systems.

Overview

A C++ header-only HTTP/HTTPS server and client library

Use Cases

Best For

Embedding a lightweight HTTP server within a C++ desktop or CLI application
Creating local API endpoints for inter-process communication in C++ services
Building IoT or edge devices that need to serve web interfaces or REST APIs
Developing HTTP clients for consuming web services in C++ projects
Serving static files or simple dynamic content without a full web framework
Adding WebSocket or Server-Sent Events support to C++ applications

Not Ideal For

High-concurrency web servers requiring non-blocking I/O for thousands of simultaneous connections
Applications targeting 32-bit architectures or requiring formal security audits on those platforms
Projects needing a full-stack web framework with built-in ORM, templating, or authentication layers
Real-time systems where WebSocket connections must scale to massive numbers without thread exhaustion

Pros & Cons

Pros

Header-Only Simplicity

Just include httplib.h to add HTTP capabilities, eliminating complex build dependencies and linking steps, as highlighted in the README's simple examples.

Comprehensive Protocol Support

Supports SSL/TLS with OpenSSL, MbedTLS, or wolfSSL backends, plus WebSocket and Server-Sent Events for real-time communication, all documented with code snippets.

Built-in Static File Serving

Offers configurable static file serving with MIME type mappings and path sanitization, reducing boilerplate code for serving web assets.

Cross-Platform Compatibility

Works on Linux, macOS, and Windows with automatic OS certificate store integration, though Windows users should use 127.0.0.1 over localhost for performance.

Cons

Blocking I/O Model

Uses blocking socket operations, limiting scalability for high-concurrency scenarios compared to asynchronous libraries; the README explicitly warns this isn't for non-blocking I/O.

Limited 32-bit Support

Officially unsupported on 32-bit platforms with potential security vulnerabilities; the maintainer states security reports for 32-bit will be closed without action.

Thread-Safety Issues

Static file server methods are marked as not thread-safe in the README, requiring careful synchronization in multi-threaded environments.

Frequently Asked Questions

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