ToolJet

ToolJet is an open-source internal-tool builder aimed at the smallest possible first win: drag a table, form or chart onto a canvas, connect one of the many advertised data sources — Postgres, MySQL, REST, GraphQL, spreadsheets — and write JavaScript where the bindings stop. It ships as hosted cloud and self-hosted alike, and its sharpest commercial move is the billing shape: you pay per builder, end users are not counted on paid tiers, so an admin panel that spreads across the company does not multiply the invoice. The free cloud tier is deliberately narrow — a couple of builders and apps — while the enterprise tier holds the governance procurement asks for: SCIM, air-gapped installation, custom AI models, plus AI generation to scaffold a first screen.

The real limitation is ecosystem size, not features on the sheet. Against Appsmith it has the smaller community and thinner documentation, so answers to awkward problems are harder to find; against Retool it is cheaper per head and noticeably less finished, with plainer widgets and fewer polished connectors. Self-hosting is an honest bargain — Docker, your network, your upgrade calendar — which also means query workers and websocket scaling become your job once concurrency grows. Pick ToolJet when a small team wants internal panels without a per-end-user seat tax and is comfortable reading source; pick Appsmith when community mass matters, and Retool when nobody wants to own a runtime.