Internal-tool builders
Internal-tool builders let teams quickly assemble dashboards and admin panels. These platforms often provide drag-and-drop UIs and connectors to databases and APIs, but they rely on developers to write custom code for business logic and seldom enforce policies across surfaces.
Feature comparison
| Feature | Retool | Appsmith | ToolJet | Budibase |
|---|---|---|---|---|
| UI builder | Drag-and-drop canvas; shape UI components easily | Visual builder with drag-and-drop widgets | Drag-and-drop UI widgets (tables, charts, forms) | Pre-built components and templates for mobile/desktop |
| Custom code & logic | Full code insertion anywhere via IDE | Logic via JavaScript or natural-language prompts in a central IDE | Supports business logic in JavaScript or Python queries | Custom logic via JavaScript; plugins and external embeds |
| Data connectors | Wide support for databases and APIs (PostgreSQL, MongoDB, GraphQL, etc.). | Connects to LLMs and databases | Built-in database; connects to PostgreSQL, MongoDB, APIs, GraphQL, SaaS | Connects to external databases, REST, CSV or built-in DB |
| Open source & self-host | Proprietary; cloud or on-prem subscription. | Open source (Apache-2.0); self-host or cloud. | Open source; self-host via Docker or cloud. | Open source; self-host via Docker/Kubernetes |
| Policy & personalisation | No built-in policy engine; personalisation limited to user roles. | No typed policy engine; customisation depends on user roles. | No policy engine; personalisation via user roles. | No policy engine; personalisation via RBAC & SSO |
ContractSpec’s differences
- Typed specifications produce both the API and UI. You define capabilities, data views and workflows, and the compiler generates code, forms and screens—no manual widget wiring.
- Policy enforcement at run time ensures PII and ABAC rules across the entire app.
- Overlay personalisation allows tenants and users to change layouts safely without code.
- Unified mobile/web runtime means you don’t need separate builders for React Native vs web.
Internal-tool builders are useful for quick dashboards. ContractSpec extends this by generating the whole stack from specs and enforcing policies throughout.