Sites like archimatetool.com

PlantUML, an open-source tool that draws UML diagrams from simple text descriptions, with a Q&A forum and German edition

Shadowfetch, a catalogue of 575 small iPhone, iPad and Mac utility apps by developer Robert Corbin

A web tool for creating and sharing text-based UML diagrams, with documentation, pricing and a changelog, run by yUML

DWSIM, an open-source chemical process simulator software project with tutorials, wiki and downloads, developed by Daniel Wagner Oliveira de Medeiros

OPNsense, an open source firewall and routing platform project with release news, blog posts, donation information and a public roadmap

LikeC4, an open source architecture-as-code tool for describing, validating and visualizing software system architecture from text source files

It's FOSS is an English-language blog on Linux tips, tutorials, applications and news, written by Abhishek Prakash

CocoaPods.org is a search and browse index for iOS, macOS and Swift library packages, with pages on the CocoaPods dependency manager

AsyncAPI, an open source initiative and specification with tools for defining and documenting event-driven architectures, under the Linux Foundation

Fiber, an Express-inspired web framework written in Go and built on the Fasthttp HTTP engine, with documentation and examples

TeaVM is an ahead-of-time compiler tool that turns Java bytecode into JavaScript and WebAssembly for web apps, with documentation

Cyotek, a software company's site offering WebCopy, CopyTools, Gif Animator and other Windows utilities, with a C# and .NET development blog

Leanpub, a self-publishing platform where authors sell early-access and in-progress books, including technical titles on software and AI

JSON Schema is a declarative language and documentation site for annotating and validating the structure and data types of JSON documents

Open WebUI, a self-hosted software platform for running and connecting AI models, with a user community and documentation

A personal website by Thomas Leitner, blog and projects on Ruby libraries, PDF tools, benchmarks and privacy

Synfig Studio is free, open-source 2D animation software for Windows, Linux and macOS, using vector and bitmap artwork

Asciidoctor, an open source Ruby text processor and toolchain converting AsciiDoc to HTML5, DocBook, PDF, and EPUB, with documentation and news

A community wiki and guide to the IndieWeb movement, promoting personal websites owned and controlled by individuals rather than corporate platforms

Remmina, an open-source remote desktop client with a news blog and project pages by developer Allan Nordhøy

The pages show only a privacy notice, so I cannot tell what the site is about: -

OpenShot, a free open-source video editing software for Linux, Mac and Windows, with a project homepage and multilingual pages

A free online tool for creating UML sequence diagrams from text, with instructions, examples and a privacy policy

Free open source 2D CAD application LibreCAD for Windows, macOS and Linux, with community support and documentation

The official website of Thunderbird, a free open-source desktop and mobile email, calendar and contacts app

JUnit, a open-source testing framework for Java and the JVM, with documentation, release notes and project information

A programming language called Gleam, a type-safe functional language running on the Erlang runtime, with its documentation and community pages

Organic Maps is a free, open-source offline maps and GPS navigation app for hiking, cycling and driving

GORM, a developer-friendly ORM library for Go, with guides, CLI and code-generation tools for database access

A documentation site for pytest, the Python testing framework, with a list of talks, books and tutorials about it

Scikit-learn, an open-source Python library of machine learning tools for predictive data analysis, with documentation, FAQ and installation guides

Node-RED, an open-source low-code tool for wiring event-driven applications and real-time data flows, with a blog and documentation

Godot Engine, a free open-source 2D and 3D game engine with a project blog and forum, with news by Thaddeus Crews and others

TecMint, a Linux how-to blog with tutorials and guides by Ravi, founded in 2012

jsDelivr is a free open source CDN service delivering JavaScript, ESM modules and other files from npm and GitHub

Personal website of Sebastián Ramírez, a Colombian software developer, sharing ideas, guides and his open source projects like FastAPI

fastlane is an open source tool for automating mobile app development, screenshots, beta distribution and store publishing

Freeter, a desktop app that organizes work by projects and tasks, with a blog on productivity and browsing