ToolJet

ToolJet positions itself as a fully open-source Retool replacement built for teams that need serious self-hosting flexibility. The visual app builder covers the expected components — tables with server-side pagination, charts, forms, maps, and kanban boards — backed by a connector library that spans SQL databases, NoSQL stores, REST and GraphQL APIs, and a long list of SaaS APIs including Stripe, Twilio, and Airtable.

Two features distinguish ToolJet from its peers. First, it ships ToolJet Database: a Postgres-backed table editor embedded in the platform that works like a lightweight Airtable inside your builder, useful for prototyping data models before connecting a production database. Second, its multiplayer editing mode lets multiple developers work on the same app canvas simultaneously, which is rare in open-source internal-tool builders and matters for teams doing active pair development.

The AGPL-3.0 license means the server is free to run on your infrastructure, but modifications distributed to external parties must be open-sourced — an important consideration for agencies building on ToolJet for clients. Audit logs, version history beyond two versions, and single sign-on require the Business plan. Deployment targets are comprehensive: Docker Compose for local setups, Helm charts for Kubernetes, and one-click options on AWS, GCP, and Azure. For developer teams that value multiplayer collaboration and want a complete Retool replacement they fully control, ToolJet covers the ground.