Analyst builds UML editor with GOST diagrams using Claude: first version in 2 hours

A systems analyst needed a UML editor that opens from Russia and doesn't require installing anything on a work machine. He couldn't find a ready-made option, so he built his own with Claude. The first working version of umleditor.ru took two hours. The site now offers GOST flowcharts with a custom renderer, a JSON editor and a reference section of 70+ pages. Diagrams are rendered by a PlantUML server deployed in Moscow.

Where the task came from

UML diagrams are part of a systems analyst's daily work. The official site plantuml.com doesn't open from Russia. That leaves local options: Java, an IDE plugin or a VPN. The author wanted none of these, especially on a corporate computer.

The solution is simple: an editor in the browser. You write PlantUML code on the left and see the diagram on the right right away. There is no registration. The author also stresses privacy. Rendering runs on his own server in Moscow, and the diagram text, which often contains names of systems, integrations and internal services, never reaches third-party platforms. For an analyst who draws diagrams for work projects, that argument matters more than a convenient interface.

Who did what

The author describes the division of labor plainly. Claude wrote the interface, the server side, the server scripts and even the reference texts. He explained what he wanted, reviewed the result and asked for rework. He also did what an AI model can't: he paid for hosting, bought the domain and entered the passwords.

The last point matters more than it seems. The model covers almost the entire development cycle, but access to money, accounts and infrastructure stays with the human. That boundary is usually where responsibility for a project sits.

Key project parameters from the author's description:

• first working version: about two hours;
• format: a web-based UML editor that updates the diagram as you type code;
• rendering: his own PlantUML server in Moscow;
• registration: not required;
• additions: GOST flowcharts with a custom renderer, a JSON editor;
• reference section: 70+ pages;
• code authorship: Claude, including server scripts and texts.

What's most interesting here

The least trivial part of the project, judging by the description, is the GOST flowcharts. Out of the box, PlantUML draws diagrams in its own style, while Russian standards require specific shapes and formatting. That's why the author needed a separate renderer. For systems analysts who submit documentation to meet customer requirements or government project rules, this is a real pain point. The diagram otherwise has to be redrawn by hand in another editor.

The original Habr article promises code and figures on how the service is built. The announcement doesn't include them, so it's not yet possible to assess the load, the server cost or the quality of the GOST renderer. It is also unclear how the service handles a large flow of requests and what protections are in place on the public rendering server. These are standard questions for any open PlantUML server.

What to take from this

The project shows a workable scenario for a specialist without a development team. You take a narrow task from your own profession, describe its solution to the model and check the result by hand. The barrier to entry is low: two hours to a first version.

Practical takeaways:

• if a work tool is unavailable because of sanctions or blocking, self-hosting PlantUML on a small server remains the simplest way to keep a familiar workflow;
• before sending diagrams to any public renderer, check that they contain no names or addresses of internal systems;
• when vibe coding, decide in advance what you do yourself: it's best not to hand payments, domains, secrets and access credentials to the model;
• test GOST diagrams on real documents before sending them to a customer.

The author promises a full technical breakdown in an article on Habr.