# open62541/open62541

Open source implementation of OPC UA (OPC Unified Architecture) aka IEC 62541 licensed under Mozilla Public License v2.0

Repository: https://github.com/open62541/open62541
Canonical: https://ross.abutalabs.com/products/open62541
Homepage: https://open62541.org
Language: C
License: MPL-2.0
License Family: copyleft
Topics: opc-ua, sdk, server, client, iec-62541, opc, c, opcua, industrial-automation, pubsub, publish-subscribe, tsn
Last push: 2026-08-26T22:28:23+00:00

## Health v2 (maintenance only)
Score: 99/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 98, longevity 100
- inputs: {"age_days": 4639, "days_push": 7, "days_rel": 13, "gap_med": 7.0, "n_releases_24m": 31}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3215, forks 1453 (observed 2026-08-28T04:07:49.568833+00:00)

## What it is
open62541 is an open-source C99 implementation of the OPC UA (IEC 62541) communication protocol for building OPC UA clients and servers or embedding OPC UA into existing applications. It is platform-independent with exchangeable plugins, runs from embedded systems to cloud servers, and is OPC UA certified.

## Use cases
- implement an OPC UA server in C
- build an OPC UA client for industrial devices
- integrate OPC UA communication into an embedded system
- add pubsub communication to industrial automation
- connect PLCs over OPC UA
- port a lightweight industrial protocol stack to an RTOS

## When to choose
- you need a certified, royalty-free OPC UA stack in C
- you target embedded or resource-constrained platforms
- you need OPC UA clients, servers, or pubsub with minimal dependencies
- you want a library combinable with proprietary software (MPLv2)

## When to avoid
- you need a high-level OPC UA toolkit in a language other than C
- you want a GUI-based OPC UA configuration tool rather than a library
- your project uses a different industrial protocol like Modbus or PROFINET

## Facets
- artifact type: library
- maturity: stable
- function: sdk, networking, middleware, iot
- domain: iot, embedded-systems
- platform: windows, embedded, cross-platform, c
- tags: opc-ua, opcua, iec-62541, industrial-automation, pubsub, client-server, c99, mpl-2.0, automation, industrial-protocols, linux, macos, android

## Member repositories
- open62541/open62541 (main) score 99

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:49.568833+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T07:24:40.656256+00:00, confidence not recorded.
  - readme: https://github.com/open62541/open62541 (fetched 2026-08-28T04:07:49.568833+00:00, sha ff1a3934b50e)
  - homepage: https://open62541.org (fetched 2026-08-29T09:38:03.018407+00:00, sha ab4c9e9856c6)
  - site_page: https://open62541.org/documentation (fetched 2026-08-29T09:38:03.021635+00:00, sha 3b7bfb7360f9)
- Data as of 2026-08-30T08:39:29.467469+00:00.