Select your cookie preferences

We use essential cookies and similar tools that are necessary to provide our site and services. We use performance cookies to collect anonymous statistics, so we can understand how customers use our site and make improvements. Essential cookies cannot be deactivated, but you can choose “Customize” or “Decline” to decline performance cookies.

If you agree, AWS and approved third parties will also use cookies to provide useful site features, remember your preferences, and display relevant content, including relevant advertising. To accept or decline all non-essential cookies, choose “Accept” or “Decline.” To make more detailed choices, choose “Customize.”

coreHTTP library - FreeRTOS

coreHTTP library

Note

The content on this page may not be up-to-date. Please refer to the FreeRTOS.org library page for the latest update.

HTTP C client library for small IoT devices (MCU or small MPU)

Introduction

The coreHTTP library is a client implementation of a subset of the HTTP/1.1 standard. The HTTP standard provides a stateless protocol that runs on top of TCP/IP and is often used in distributed, collaborative, hypertext information systems.

The coreHTTP library implements a subset of the HTTP/1.1 protocol standard. This library has been optimized for a low memory footprint. The library provides a fully synchronous API so applications can completely manage their concurrency. It uses fixed buffers only, so that applications have complete control of their memory allocation strategy.

The library is written in C and designed to be compliant with ISO C90 and MISRA C:2012. The library's only dependencies are the standard C library and LTS version (v12.19.1) of the http-parser from Node.js. The library has proofs showing safe memory use and no heap allocation, making it suitable for IoT microcontrollers, but also fully portable to other platforms.

When using HTTP connections in IoT applications, we recommend that you use a secure transport interface, such as one that uses the TLS protocol as demonstrated in the coreHTTP mutual authentication demo.

This library can be freely used and is distributed under the MIT open source license.

Code Size of coreHTTP (example generated with GCC for ARM Cortex-M)
File With -O1 Optimization With -Os Optimization
core_http_client.c 3.2K 2.6K
api.c (llhttp) 2.6K 2.0K
http.c (llhttp) 0.3K 0.3K
llhttp.c (llhttp) 17.9 15.9
Total estimates 23.9K 20.7K
PrivacySite termsCookie preferences
© 2025, Amazon Web Services, Inc. or its affiliates. All rights reserved.