Weak copyleft open-source software in 2026
Changes to the licensed files must be shared, but you can link them into a closed program. 71 projects here use LGPL-2.1 (10), LGPL-3.0 (21), MPL-2.0 (36), EPL-1.0 (1) and EPL-2.0 (3).
-
1
Syncthing syncthing
Open Source Continuous File Synchronization
Complete system Production-ready You want folders kept in sync across your computers and servers without a cloud provider.
★ 90k MPL-2.0 Go Active, pushed today -
2
Penpot penpot
Penpot: The open-source design platform for Product teams that need scalable collaboration.
Complete system Production-ready Your team wants a Figma alternative it can self-host or use without per-editor lock-in.
★ 62k MPL-2.0 Clojure Active, pushed today -
3
OCRmyPDF ocrmypdf
OCRmyPDF adds an OCR text layer to scanned PDF files, allowing them to be searched
Developer tool Production-ready You have scanned PDFs that need to become searchable, in batch or a pipeline.
★ 35k MPL-2.0 Python Active, pushed 9 days ago -
4
FreeCAD FreeCAD
Official source code of FreeCAD, a free and opensource multiplatform 3D parametric modeler.
Complete system Production-ready Engineers, makers or small firms need free parametric CAD without SolidWorks or Fusion licences.
★ 35k LGPL-2.1 C++ Active, pushed today -
5
Platform hcengineering
Huly — All-in-One Project Management Platform (alternative to Linear, Jira, Slack, Notion, Motion)
Complete system Usable Only for existing installs; new users should look at the Platform-Collective fork.
★ 28k EPL-2.0 TypeScript Active, pushed 5 days ago -
6
SOPS getsops
Simple and flexible tool for managing secrets
Developer tool Production-ready You keep infrastructure config in Git and want secrets encrypted alongside it, often with Flux or Helm.
★ 24k MPL-2.0 Go Active, pushed today -
7
Vector vectordotdev
A high-performance observability data pipeline.
Complete system Production-ready You need a fast, single-binary agent or aggregator to reshape and ship telemetry, for example to cut observability costs.
★ 23k MPL-2.0 Rust Active, pushed today -
8
Sonic valeriansaliou
🦔 Fast, lightweight & schema-less search backend. An alternative to Elasticsearch that runs on a few MBs of RAM.
Building block Usable You need fast autocomplete and text search on a small server and can store documents elsewhere.
★ 21k MPL-2.0 Rust Active, pushed 3 days ago -
9
ActivityWatch ActivityWatch
The best free and open-source automated time tracker. Cross-platform, extensible, privacy-focused.
Complete system Production-ready You want private automatic time tracking without a cloud service.
★ 19k MPL-2.0 Python Active, pushed 7 days ago -
10
Logto logto-io
🧑🚀 Authentication and authorization infrastructure for SaaS and AI apps, built on OIDC and OAuth 2.1 with multi-tenancy, SSO, and RBAC.
Building block Production-ready You want an Auth0-like service with ready sign-in screens that you can self-host or use as cloud.
★ 15k MPL-2.0 TypeScript Active, pushed today -
11
VNote vnotex
A pleasant note-taking platform with native speed, majoring in Markdown, MindMap, Typst, and plain text.
Complete system Usable You want a fast desktop Markdown notes app rather than an Electron one.
★ 13k LGPL-3.0 C++ Active, pushed today -
12
BigBlueButton bigbluebutton
A complete web conferencing system for virtual classes and more!
Complete system Production-ready A school, university or training provider needs online classes integrated with Moodle, Canvas or another LMS on its own servers.
★ 9.3k LGPL-3.0 TypeScript Active, pushed today -
13
OpenBao openbao
OpenBao is a software solution to manage, store, and distribute sensitive data including secrets, certificates, and keys.
Complete system Production-ready You need Vault-style secrets management but want to avoid HashiCorp's BSL license.
★ 8.8k MPL-2.0 Go Active, pushed today -
14
PixiEditor PixiEditor
PixiEditor is a Universal Editor for all your 2D needs
Complete system Usable Indie game developers or artists want a free editor for sprites and simple animation.
★ 8.1k LGPL-3.0 C# Active, pushed today -
15
Alda alda-lang
A music programming language for musicians. :notes:
Developer tool Usable You are a musician or programmer who wants to write music in a text editor.
★ 6k EPL-2.0 Go Active, pushed 10 days ago -
16
Kanidm kanidm
Kanidm: A simple, secure, and fast identity management platform
Complete system Usable You want a modern self-hosted replacement for FreeIPA or OpenLDAP to manage people and Linux logins.
★ 5.5k MPL-2.0 Rust Active, pushed today -
17
Joint clientIO
A proven SVG-based JavaScript diagramming library powering exceptional UIs
Building block Production-ready You are building a diagramming or visual modelling feature into a web app and want a mature open-source core.
★ 5.4k MPL-2.0 JavaScript Active, pushed 4 days ago -
18
Docker-volume-backup offen
Backup Docker volumes locally or to any S3, WebDAV, Azure Blob Storage, Dropbox, Google Drive or SSH compatible storage
Complete system Production-ready You run services with Docker Compose or Swarm and want volume backups added as one more service.
★ 4.1k MPL-2.0 Go Active, pushed today -
19
Mapnik mapnik
Mapnik is an open source toolkit for developing mapping applications
Building block Production-ready You render your own map tiles or images from GIS data.
★ 4k LGPL-2.1 C++ Active, pushed today -
20
IRremoteESP8266 crankyoldgit
Infrared remote library for ESP8266/ESP32: send and receive infrared signals with multiple protocols. Based on: https://github.com/shirriff/Arduino-IRremote/
Building block Production-ready You are building an ESP-based IR blaster or receiver, for example to control air conditioners.
★ 3.7k LGPL-2.1 C++ Active, pushed 2 months ago -
21
Open62541 open62541
Open source implementation of OPC UA (OPC Unified Architecture) aka IEC 62541 licensed under Mozilla Public License v2.0
Building block Production-ready You are writing firmware or software that must speak OPC UA and want a portable, open implementation.
★ 3.3k MPL-2.0 C Active, pushed 5 days ago -
22
OCCT Open-Cascade-SAS
Open CASCADE Technology (OCCT) is an open-source software development platform for 3D CAD, CAM, CAE.
Building block Production-ready You are building CAD, CAM or CAE software and need an open B-rep kernel.
★ 3.1k LGPL-2.1 C++ Active, pushed 13 days ago -
23
Pikepdf pikepdf
A Python library for reading and writing PDF, powered by QPDF
Building block Production-ready Python code needs to manipulate PDF structure, metadata, pages or encryption reliably, including damaged files.
★ 2.8k MPL-2.0 Python Active, pushed yesterday -
24
Pythonocc-core tpaviot
Python package for 3D geometry CAD/BIM/CAM
Building block Production-ready You build CAD or engineering tools in Python and need full OpenCascade access.
★ 2k LGPL-3.0 SWIG Active, pushed today -
25
Vigil valeriansaliou
🚦 Microservices Status Page. Monitors a distributed infrastructure and sends alerts (Slack, SMS, etc.).
Complete system Production-ready You want a lightweight, efficient status page for a set of services and are happy configuring it in TOML.
★ 1.9k MPL-2.0 Rust Active, pushed 23 days ago -
26
SpiffWorkflow sartography
A powerful workflow engine implemented in pure Python
Building block Usable You need to run BPMN workflows inside a Python application.
★ 1.9k LGPL-3.0 Python Active, pushed 4 days ago -
27
Daptin daptin
Self-hosted application server for schema-driven APIs, identity, files, automation, integrations, realtime, metering, and protocols.
Framework or platform Usable You want a self-hosted backend-as-a-service in one binary and prefer config over writing CRUD code.
★ 1.9k LGPL-3.0 Go Active, pushed today -
28
Cypht cypht-org
Cypht: Lightweight Open Source webmail aggregator [PHP, JS]. Supports IMAP/SMTP, JMAP and EWS (Exchange Web Services)
Complete system Production-ready You want a lightweight self-hosted webmail that aggregates mailboxes from different providers.
★ 1.8k LGPL-2.1 PHP Active, pushed today -
29
DataGear datageartech
DataGear数据可视化分析平台，自由制作任何数据看板
Complete system Usable A Chinese-speaking team wants a free, flexible dashboard builder on Java.
★ 1.7k LGPL-3.0 Java Active, pushed 14 days ago -
30
Git-commit-id-maven-plugin git-commit-id
Maven plugin which includes build-time git repository information into an POJO / *.properties). Make your apps tell you which version exactly they were built from! Priceless in large distributed deployments... :-)
Developer tool Production-ready You build Java services with Maven and need build version info exposed at runtime or in health endpoints.
★ 1.7k LGPL-3.0 Java Active, pushed 43 days ago -
31
Opcua-asyncio FreeOpcUa
OPC UA library for python >= 3.10
Building block Production-ready You need to read from or expose OPC UA data in a Python script or service.
★ 1.5k LGPL-3.0 Python Active, pushed 23 days ago -
32
Horilla-hr horilla
Horilla is a free and open source HR software.
Complete system Usable A small or mid-size company wants a free self-hosted HR suite and has someone to run Django.
★ 1.5k LGPL-2.1 HTML Active, pushed 6 days ago -
33
Neuron emqx
Open source industrial connectivity server
Complete system Production-ready You need a lightweight edge gateway to move PLC data into MQTT or EMQX.
★ 1.4k LGPL-3.0 C Active, pushed 5 days ago -
34
Milo eclipse-milo
Eclipse Milo™ - an open source implementation of OPC UA (IEC 62541).
Building block Production-ready You build industrial or IoT software on the JVM and need a mature OPC UA client or server.
★ 1.4k EPL-2.0 Java Active, pushed 5 days ago -
35
Tab Stash josh-berry
Firefox extension to save and restore tabs as bookmarks. Clear your tabs, clear your mind.
Complete system Production-ready You use Firefox and keep too many tabs open but want to save them rather than close them.
★ 1.1k MPL-2.0 TypeScript Active, pushed yesterday -
36
xTools x-tools-author
xTools: Qt-SerialPort-HID-BLE-UDP-TCP-WebSocket-Modbus-CANBus-MQTT-CoAP-TFTP-mDNS debugging tool, which support custom lua, javascript, chart view and data transmitting...
Developer tool Usable An embedded or hardware developer wants one desktop tool for poking at many communication links.
★ 1.1k LGPL-3.0 C++ Active, pushed 17 days ago -
37
DSS esig
Digital Signature Service : creation, extension and validation of advanced electronic signatures
Building block Production-ready You build software that must produce or validate eIDAS-compliant signatures in the EU.
★ 1k LGPL-2.1 Java Active, pushed 19 days ago -
38
OpenRPA open-rpa
Free Open Source Enterprise Grade RPA
Complete system Usable You want free desktop RPA on Windows with orchestration of several robots.
★ 3.1k MPL-2.0 C# Slowing, pushed 7 months ago -
39
OpenBoxes openboxes
OpenBoxes is a warehouse management system designed to manage inventory and track stock movements for healthcare facilities.
Complete system Production-ready A health facility, NGO or distributor needs stock tracking that works in low-resource settings.
★ 920 EPL-1.0 Groovy Active, pushed 4 days ago -
40
Groonga groonga
An embeddable fulltext search engine. Groonga is the successor project to Senna.
Building block Production-ready You need fast full-text search over Japanese or other CJK text, especially inside MySQL or Postgres.
★ 859 LGPL-2.1 C Active, pushed 5 days ago -
41
Ableton-Linux shibco
Run Ableton 12 and Push on Linux
Integration Experimental You own Ableton Live and want to move your studio to Linux.
★ 825 LGPL-2.1 Shell Active, pushed 8 days ago -
42
Zeabur zeabur
A platform that helps you deploy services with one click.
List, course or other material Production-ready You want to learn about or use Zeabur's hosted platform; for the platform itself look at the zeabur.com service.
★ 737 MPL-2.0 HTML Active, pushed 2 days ago -
43
Webauthn-rs kanidm
An implementation of webauthn components for Rustlang servers
Building block Usable You add passkey authentication to a Rust web service.
★ 717 MPL-2.0 Rust Active, pushed 4 days ago -
44
Backend.AI lablup
Backend.AI is a streamlined, container-based computing cluster platform that hosts popular computing/ML frameworks and diverse programming languages, with pluggable heterogeneous accelerator support including CUDA GPU, ROCm GPU, Gaudi NPU, Google TPU, GraphCore IPU and other NPUs.
Complete system Production-ready A research lab or company runs a shared GPU cluster and needs multi-user scheduling across mixed accelerator hardware.
★ 677 LGPL-3.0 Python Active, pushed today -
45
Quillforms quillforms
Open Source TypeForm Alternative Based on React JS and Typescript | Best Typeform Clone | Conversational Multi Step Form
Complete system Production-ready Your site runs on WordPress and you want Typeform-like forms without a Typeform subscription.
★ 622 LGPL-3.0 JavaScript Active, pushed today -
46
Nixflix kiriwalawren
NixOS Media Server Configuration
Template or starter Usable You run NixOS and want your whole media stack defined in configuration.
★ 611 MPL-2.0 Nix Active, pushed 2 days ago -
47
Aw-watcher-web ActivityWatch
Browser watcher for ActivityWatch
Integration Production-ready You use ActivityWatch and want per-site detail in your time reports.
★ 564 MPL-2.0 TypeScript Active, pushed 23 days ago -
48
Appointment thunderbird
Invite others to grab times on your calendar. Choose a date. Make appointments as easy as it gets.
Complete system Usable You want a privacy-minded Calendly alternative, hosted by Thunderbird Pro or self-run.
★ 556 MPL-2.0 Python Active, pushed 3 days ago -
49
FacturaScripts NeoRazorX
Open source ERP software. Built on modern PHP and bootstrap. Easy and powerful.
Complete system Production-ready A small business in Spain or Latin America wants free invoicing and accounting with local tax plugins.
★ 501 LGPL-3.0 PHP Active, pushed 7 days ago -
50
Superstreamer superstreamerapp
An open, scalable, online streaming setup. All-in-one toolkit from ingest to adaptive video playback. Built for developers in need of video tooling.
Complete system Usable You need your own video-on-demand pipeline from upload to adaptive playback without paying a video API vendor.
★ 1.5k MPL-2.0 TypeScript Slowing, pushed 9 months ago -
51
SignServer CE Keyfactor
SignServer – Open source, PKI-based signing software to sign code, documents, timestamps and more.
Complete system Production-ready Your organisation needs central, audited code or document signing with keys kept off developer machines.
★ 441 LGPL-2.1 Java Active, pushed 2 months ago -
52
Redlamp pdcgomes
A native, open-source RAW photo editor for Mac, iPad and iPhone that feels immediately familiar to Lightroom users.
Complete system Experimental You are a photographer on Apple Silicon who wants to follow an open Lightroom alternative early.
★ 367 MPL-2.0 Swift Active, pushed today -
53
PiBar amiantos
PiBar for Pi-hole - Manage your Pi-hole(s) from your macOS menu bar!
Complete system Usable You use a Mac and often need to pause Pi-hole briefly to get a blocked site working.
★ 344 MPL-2.0 Swift Active, pushed 42 days ago -
54
MagnusBilling magnussolution
MagnusBilling is a fast, secure, efficient, high availability, VOIP Billing.
Complete system Production-ready A small VoIP provider, call shop or calling-card business needs Asterisk-based billing on a dedicated server.
★ 337 LGPL-3.0 JavaScript Active, pushed 3 months ago -
55
Awatcher 2e3s
Activity and idle watchers
Integration Usable You use ActivityWatch on Linux and the default watchers do not support your desktop.
★ 318 MPL-2.0 Rust Active, pushed 41 days ago -
56
StatsHouse VKCOM
StatsHouse is a highly available, scalable, multitenant monitoring system
Complete system Usable You run very large fleets producing high-cardinality metrics and can run ClickHouse underneath.
★ 276 MPL-2.0 Go Active, pushed 3 days ago -
57
SyncUp sidtech-solutions
SyncUp: an open-source Syncthing client for iOS and Android, powered by react-native
Complete system Usable You use Syncthing and need a maintained mobile client, especially on iOS, since the official Android app was archived.
★ 245 MPL-2.0 TypeScript Active, pushed 6 days ago -
58
Alfresco-community-repo Alfresco
Community Content Service Repository
Building block Production-ready You build or maintain an Alfresco Community installation and need the repository source.
★ 240 LGPL-3.0 Java Active, pushed 6 days ago -
59
WebErpMesv2 SMEWebify
Open-source ERP/MES for sheet metal, machining and mold shops. From quote to invoice: routings, BOMs, shop-floor tracking, finite-capacity planning, stock by dimensions, quality and Factur-X e-invoicing. Built by people who run workshops.
Complete system Usable A small job shop doing sheet metal or machining, especially in France, wants open-source quoting, planning and shop-floor tracking.
★ 224 LGPL-3.0 PHP Active, pushed 12 days ago -
60
Platform lsfusion
lsFusion is an extremely declarative open-source language-based platform for information systems development
Framework or platform Usable You build data-heavy business systems such as ERP or retail back office and are open to a fundamentally different development model.
★ 214 LGPL-3.0 Java Active, pushed today
Other license families
This is a plain summary, not legal advice. The license text in each repository is what binds.