This guide features 15 open source alternatives to popular paid tools trending in 2025. Six have been used in real projects, and the rest are chosen from careful research and community reviews. Treat this as a discovery guide, not an endorsement.
If you're more of a visual learner, I recommend checking out my YouTube tutorial. It covers everything step-by-step:
Open Source Software I Tested
n8n
n8n is a strong Zapier alternative for automation. Connect apps and services, automate social media posting, sync spreadsheets and databases, or trigger notifications. Offers visual low-code workflows with over 4000 templates. There's a paid cloud version, and a self-hosted community version under the Sustainable Use License for internal business or non-commercial use.
Ollama
Ollama installs Llama 3, Mistral, Deepseek, Gemma, and other models with one command. Works offline, no token limits, and supports both CLI and REST API. Licensed under MIT and Apache, so the core and integrations are open and modifiable. Pair with Open WebUI for a ChatGPT-like interface. For GPUs with under 8GB VRAM, use 8B models or smaller.
You'll find installation guides here:
Taiga
Taiga is a project management tool similar to Jira. It includes Kanban, Scrum, epics, backlog, and issue tracking. Self-host in Docker under Mozilla Public License 2.0. Works well for advanced needs, though setup is heavy for basic boards. Free cloud version allows private and commercial use with limits on users and features.
Zettlr
Zettlr is a note-taking app for research. Features citation management, split view, links, and many exports. Uses plain markdown files, so you store and move notes freely. Zettlr runs under GPLv3, supporting both personal and commercial use without restrictions. Obsidian is easier for day-to-day notes but isn’t open source.
CrewAI
CrewAI builds teams of AI agents for complex workflows. Set up agents with defined roles to handle project tasks. Used with Ollama's local models or cloud LLMs. Requires Python. Fully open source; data stays on your own server.
You'll find a how-to-guide here: The Ultimate Guide to CrewAI Agents with Ollama
Bitwarden
Bitwarden is a password manager like 1Password or LastPass. Free individual cloud plan supports unlimited devices and storage. Self-host Bitwarden for full control. Licensed GNU GPL v3.0 for personal or business use.
Open Source Software I Researched
These next open source tools I have not tried myself, but I researched them carefully:
LibreOffice
LibreOffice is an office suite for documents, spreadsheets, and presentations. Offline alternative to Microsoft Office.
Mattermost
Mattermost is a team chat platform replacing Slack and Microsoft Teams. Self-host for privacy and add plugins without fees.
NocoDB
NocoDB transforms SQL databases into collaborative spreadsheets. Grid, kanban, and calendar views with automation.
AppFlowy
AppFlowy is a Notion-style workspace. Works offline, supports mobile and desktop, and stores files locally.
Jitsi
Jitsi is a secure self-hosted video calls and group meetings instead of Zoom or Google Meet.
ERPNext
ERPNext is a full business management suite covering accounting, inventory, CRM, HR, etc. Alternative to SAP.
BookStack
BookStack is a self-hosted platform for organizing IT documentation by book, chapter, and page.
Element
Element is a messenger using the Matrix protocol as an alternative to WhatsApp, Slack, and Teams. Self-host for privacy with end-to-end encryption.
Gemini CLI
Gemini CLI: brings Google’s Gemini models to your terminal for code generation, review, and agent workflows. Apache 2.0 license, used instead of paid tools like GitHub Copilot. Free tier has usage limits.
Share Your Experience
If any of these tools spark ideas, try them and share your experience. Your feedback helps others find reliable, cost-saving open source options.