New The agentic interface — describe your app, get it running

Better software, faster.

BESSER is an open-source low-code platform to quickly build all types of (smart) applications. Model it or simply describe it — then generate APIs, databases, agents, and full deployments.

Start now — open the editor See our features Star on GitHub

Describe it, check the model, run the app — the agentic interface of the BESSER editor. No installation required.

Generates for the stacks you already use

PythonFastAPIReactDjangoSpring BootFlutterSQLAlchemySQLJavaPyTorchTensorFlowQiskitDockerTerraform
New · Agentic interface

Describe your app. Check the model. Get it running.

The editor now asks how you want to build. Draw the system yourself, or describe it in plain words and let an agent build it with you — on the same models, in the same editor.

Low-code · visual

Model it

Draw your system precisely — classes, relationships, state machines, screens. BESSER’s generators turn the models into code: same model in, same code out, every run.

Agentic · natural language

Describe it

Say what you want in plain words. An assistant builds the models with you, then the application from them — and you refine both by chatting.

What you can ask it for

Models from a sentence

Describe your domain and get a B-UML model you can check before any code exists.

  • Class, object, state-machine, agent, user, GUI, quantum-circuit and BPMN diagrams
  • Typed attributes, associations, enumerations and OCL rules
  • Edit by chatting or on the canvas — both change the same model

Code straight from the generators

Ask for a target BESSER already templates and the code comes from the generator itself — no language model involved.

  • An SQL schema for PostgreSQL, a Django project, a FastAPI back-end, …
  • Deterministic: same model, same code — 0 tokens spent
  • Ready to download in seconds

Whole applications

Ask for “the web app” and the Spec-Driven Agent builds it: generators first, AI only for the gap, tested before it is handed over.

  • A running back-end and front-end, e.g. FastAPI + React
  • Features the templates don’t cover — auth, JWT, Docker, migrations, tests
  • Stacks with no BESSER generator — Next.js, Rails, Rust/Axum, Kotlin/Spring
Describe your app How the Spec-Driven Agent works Free hosted model · no account · open source
What BESSER gives you

A complete low-code toolchain — open, AI-powered, and modular.

From a single model, BESSER produces working software: APIs, databases, full back-ends, AI agents, and deployment manifests.

See all features

25+ generators

Model once, then generate for many targets. BESSER ships generators for databases, REST APIs, web apps, AI agents, and deployment manifests out of the box. A single model becomes working software across platforms.

  • Databases, REST APIs, web apps
  • AI agents and deployment manifests
  • 25+ targets from one model

AI-powered

BESSER combines AI with low-code at every step. Describe your system and the assistant builds the model; ask for the app and the Spec-Driven Agent builds it on top of BESSER’s generators. And the software you generate can embed AI components — agents, neural networks, LLM calls.

  • Describe it — the assistant builds B-UML models
  • Spec-Driven Agent — generators first, AI for the gap
  • Generate software with embedded AI

Two ways to build

Different users, one editor. Draw your system precisely on the canvas, or describe it in plain words and let the assistant build the model with you — attach a sketch or a screenshot if you have one. Both lead to the same models, so you can switch at any time.

  • Model it: the visual canvas
  • Describe it: the natural-language assistant
  • Attach sketches or screenshots

Model anything

BESSER covers the dimensions a real system needs: class, object, state-machine, agent, user, GUI, BPMN, quantum-circuit, neural-network, deployment and knowledge-graph diagrams. All built in, all in one project.

  • Class, object, state-machine & BPMN diagrams
  • Agents, users, GUIs and deployment
  • Neural networks, quantum circuits & knowledge graphs

Business rules enforcement

B-OCL brings the OCL support to BESSER. Define invariants, pre/post conditions directly on your B-UML models. The built-in parser and interpreter validate constraints instantly, and the code generator enforces them in the target framework — no re-implementation needed.

  • Invariants, pre/post conditions
  • Live validation via Quality Check
  • Constraints enforced in generated code

Open source & free

BESSER is open source under the MIT license. Use the hosted editor in your browser with nothing to install and no account, run it locally, or extend it with your own generators and diagram types.

  • MIT license
  • Hosted editor, no account needed
  • Run locally or extend it
View on GitHub
25+
Code generators
67
Research papers
11
Researchers & engineers
2
EU Horizon projects
How it works

Model once. Generate everything.

From a single, simple model — code, infrastructure, AI agents, and deployments fall out the other side.

Model

Start your model with drag-and-drop diagramming in the editor, then refine details with forms and structured views. Prefer words to boxes? Choose Describe it and the assistant builds the model from a plain-language description — then polish it by chatting or on the canvas.

Wondering whether BESSER is right for you?

Open the editor and try it in your browser, or talk to us — we love a good problem statement.

Try BESSER Let’s chat