rombik API

HTTP API for flowcharts & structograms from your scripts. Authenticate with the X-API-Key header.

Full API reference

All endpoints, parameters, code samples in several languages and try-it — interactive, on its own page.

Open the reference →

What /render can do

One endpoint, more knobs than it looks. Everything below is a parameter of the same call.

10 languages: python, cpp, c, java, csharp, pascal, javascript, typescript, php, go — plus rombik: your own chart tree (astJSON) for any other language.
14 formats: docx, visio, drawio, typst, excalidraw, svg, png, jpeg, webp, gif, gif_anim, pdf, html, json — docx and visio come out as native shapes you can keep editing.
Images and a web page: jpeg — a raster on white; webp — lossless and lighter than png; gif — static, 256 colours; gif_anim — the chart draws itself block by block, on a loop; html — the chart and the code with line numbers on one page. With json: true rasters come back base64 like png, and html comes as text like svg.
Two diagram kinds: mode: "flow" — a standard flowchart; mode: "nsd" — a Nassi-Shneiderman structogram.
Source: code or a link: pass url instead of code: raw.githubusercontent.com, gist, gitlab, bitbucket, codeberg (github.com/…/blob/… links normalize themselves).
Batches up to 100 sources: /render/batch builds a multi-page PDF or a zip; the response carries X-Rombik-Rendered and X-Rombik-Failed headers.
Fine tuning: the options object: locale, your own words on the yes/no branches, terminators, figure numbering, scale, font. Tall charts split with A/Б connectors via split.
Poster: format: "poster" — code and chart side by side in one image for social media.

Integrations & tools

For AI agents

A ready-made skill in the open Agent Skills format — Claude Code, Codex, GitHub Copilot, Cursor, Gemini CLI and more.

Install into your agent

npx skills add OlexiyOdarchuk/rombik-skill

Skill on GitHub →

Download skill (.md) View

rombik CLI

Work with the API straight from your terminal.

macOS / Linux

curl -fsSL https://rombik.app/install.sh | sh

Windows commands▾

Windows (PowerShell)

ps1

irm https://rombik.app/install.ps1 | iex

Windows (CMD)

cmd

curl -fsSL https://rombik.app/install.cmd -o "%TEMP%\rombik-install.cmd" && "%TEMP%\rombik-install.cmd"

All commands▾

rombik auth                                   # sign in via the browser (or: rombik auth rk_…)
rombik render main.py -f pdf -o chart.pdf
rombik render app.ts -f drawio -o app.drawio
rombik render main.go --structogram -f svg    # Nassi-Shneiderman structogram
cat prog.cpp | rombik render - --lang cpp -f png -o prog.png
rombik render --url https://raw.githubusercontent.com/…/main.py -f svg
rombik render main.py -f pdf --link           # plus a temporary link to the result
rombik batch src/*.py -f pdf -o project.pdf   # many sources at once
rombik me                                     # plan and monthly limit
rombik products                               # plan catalog
rombik topup 3                                # payment link for the plan with id 3
rombik mcp                                    # MCP server over stdio
rombik version --json                         # {version, latest, updateAvailable}
rombik update                                 # update to the latest version
rombik logout                                 # remove the saved key

The key is never passed as an argument — only via the ROMBIK_API_KEY variable or the config written by “rombik auth”. The API base is ROMBIK_API_URL. Full flag list: “rombik render -h”.

Install manually▾

The install command above auto-detects your system. These are direct binary links.

macOS · Apple Silicon (M1–M4)macOS · Intel Linux · Intel / AMD (64-біт)Linux · ARM (64-біт)Windows · Intel / AMD (64-біт)Windows · ARM (64-біт)

MCP server

The agent gets render_flowchart, balance, products, topup_link. Two ways in: a remote server — no install at all, or locally via the CLI (stdio).

Remote — no install

url

https://rombik.app/mcp

Paste the address into your MCP client (ChatGPT connectors, Claude, Cursor…) — sign-in opens in the browser by itself (OAuth), no keys to type. Access is revocable in your account.

Claude Code

claude mcp add --transport http rombik https://rombik.app/mcp

Clients with a JSON config

json

{
  "mcpServers": {
    "rombik": { "url": "https://rombik.app/mcp" }
  }
}

Locally via the CLI (stdio)▾

Install the CLI and run “rombik auth” first, then add the config to your client. The key lives in a config file and never enters the model context.

Claude Code

claude mcp add rombik -- rombik mcp

Cursor / Windsurf (JSON)

json

{
  "mcpServers": {
    "rombik": { "command": "rombik", "args": ["mcp"] }
  }
}

Temporary links to a result

When there is nowhere to show the file — a chat bot, a webhook, an email — hand out a link instead of bytes. Post the render result to /r and get a public address that lives an hour: images and PDFs open right in the browser, everything else downloads. The CLI does the same with --link, and remote MCP uses the same store.

Sign in with rombik

Your app can ask people to sign in with their rombik account. The user sees a consent page with your app name, clicks “Allow” — and you get an API key that renders charts under their plan. It is plain OAuth 2.0 (authorization code + PKCE) with OpenID Connect on top, so any standard library works.

1 Register your app

One call to /oauth/register with a name and redirect URIs returns a client_id. Registration is open — no approval to ask for. A server-side app also gets a secret; a mobile app, SPA or CLI needs none — PKCE protects those.
2 Get the user’s consent

Open the /oauth/authorize page for them. They see your app name, click “Allow” and come back to your address with a one-time code. The code lives 10 minutes.
3 Exchange the code for a token

A call to /oauth/token with the code and the PKCE check returns an access_token. It is a regular rombik API key — no separate logic after that, every endpoint works. The openid scope adds an id_token with the identity to the same response.
4 Act on the user’s behalf

Who they are — /oauth/userinfo; keys to verify the id_token signature — /oauth/jwks. Then plain /render — under the user’s plan.

Libraries with discovery support configure themselves — give them the metadata URLs: https://rombik.app/.well-known/oauth-authorization-server https://rombik.app/.well-known/openid-configuration

Worth knowing

•Rendering runs under the plan of the user who consented (Pro required), not yours.
•The token does not expire. The user can revoke access in their account at any time — the key disappears and calls start returning 401.
•PKCE (S256) is mandatory for clients without a secret; the plain method is rejected.
•Instead of registering, client_id may be an https URL to your app’s metadata document — such a client is always treated as public.
•The app name from the consent page is what the user sees in the access list in their account.

Parameters, response fields and try-it — in the API reference →

Рідний формат rombik / rombik native format

For unsupported languages, use lang:"rombik" and pass astJSON (requires Pro).

Full specification — /api/v1/rombik-format.md.

view the spec →

So, what does it cost?

No separate “API pricing”: API, CLI and MCP come with the Pro plan together with the editor — the same monthly export limit as on the site. Get it on the pricing page or via topup_link in MCP.

Pricing →

Ready to start?