Got it 👍 — you’re asking: what are the most stable, reliable, production-ready open source web applications that people actually use in the market today (not just boilerplates or hobby projects).
Here’s a breakdown by category, focusing on maturity, large communities, and proven production adoption:
🔹 Content Management Systems (CMS)
These are the backbone of many SaaS and marketplace applications.
- Drupal — enterprise-grade, stable, modular, great for complex multi-tenant or marketplace use cases.
- WordPress — world’s most popular CMS, massive ecosystem, plugins for almost any functionality.
- Joomla — less popular now, but still stable, often used for community portals.
🔹 E-commerce & Marketplaces
Proven platforms for transactions, vendors, and bidding.
- Magento Open Source (Adobe Commerce) — powerful for multi-vendor marketplaces, very mature.
- Drupal Commerce — tightly integrated with Drupal, reliable for custom SaaS marketplaces.
- PrestaShop — widely used in Europe, stable for small/mid businesses.
- Odoo Community — ERP + e-commerce + bidding/procurement apps, very stable.
- ERPNext — open-source ERP with tender/bidding features, reliable in enterprise deployments.
🔹 Collaboration / Community Platforms
Good for marketplaces with strong networking or vendor-customer interactions.
- Discourse — leading open-source forum/community platform.
- Open Social (Drupal distribution) — enterprise-grade community SaaS, actively maintained.
- Flarum — lightweight community discussion platform.
🔹 Project / Job Marketplaces (closest to Upwork / Fiverr)
Open-source solutions built for freelance-style platforms.
- Sharetribe (Go open-source) — widely adopted for peer-to-peer marketplaces.
- Cocorico — reliable Symfony-based marketplace framework (bookings, bidding, services).
- JoomBri Freelance (Joomla extension) — stable, focused freelance marketplace system.
- WordPress Jobster / FreelanceEngine (themes/plugins) — proven, though not as flexible as Drupal/Sharetribe.
🔹 Enterprise-grade Collaboration / Business Apps
Stable bases for extending into SaaS.
- Nextcloud — reliable open-source collaboration/storage suite.
- Redmine — project management, issue tracking (stable for years).
- GitLab Community Edition — code collaboration and DevOps platform, widely used.
✅ Most stable + reliable (large user base + long-term support):
- Drupal (for CMS/multi-tenant frameworks)
- Odoo or ERPNext (for ERP + bidding)
- Magento Open Source (for e-commerce/marketplaces)
- Sharetribe Go (for peer-to-peer marketplaces)
👉 If your goal is specifically a Fiverr/Upwork-style SaaS, the most stable & reliable open-source starting points today would be:
- Sharetribe Go (if you want quickest path to market, then extend/customize).
- Drupal + Commerce + Domain Access (or Tenant) (if you want multi-tenant SaaS with flexibility + long-term enterprise stability).
- Cocorico (Symfony-based) (if you prefer a PHP framework marketplace out of the box).