What you get for nothing.
The Lucid Train CLI is free and open source with no time limit, and running it against a local Ollama model costs nothing at all since there are no API charges. The desktop app, which is where the visual diagram canvas lives, has a 7-day trial with no card required and is then $3 a month.
Free forever: the CLI
A single 6 MB Rust binary with a keyboard-first terminal interface. Same agent core as the desktop app, same model support, same configuration file. No account needed, no time limit, and the source is open.
Free to run: local models
Point it at a local Ollama model and the marginal cost of every turn is zero. No API key, no telemetry, and nothing leaves the machine. This is the part people miss when comparing prices: most tools in this category bundle model usage into a subscription, so you are paying for tokens whether or not you wanted to.
Free for a week: the desktop app
The trial is granted on first sign-in, lasts seven days and needs no card. It is an entitlement on your account rather than a payment subscription, so there is nothing to cancel and nothing is charged when it lapses. After that the app is $3 a month or $30 a year, covering up to three devices.
What each one includes
| CLI | Desktop app | |
|---|---|---|
| Price | Free, open source | 7-day trial, then $3/month |
| Coding agent | Yes | Yes |
| Reviewable diffs | Yes | Yes |
| Any OpenAI-compatible model | Yes | Yes |
| Fully offline with local models | Yes | Yes |
| MCP server and client | Yes | Yes |
| Diagram canvas | No | Yes |
| Version history | No | Yes, 50 per diagram |
| Dependency audit | No | Yes |
| Grafana, Prometheus, Loki | No | Yes |
| Runs over SSH | Yes | No |
Questions about pricing
Is there a free architecture diagram tool?
The Lucid Train CLI is free and open source with no time limit, and running it against a local Ollama model costs nothing at all because there are no API charges. The desktop app, which is where the visual diagram canvas lives, has a 7-day trial with no card required and is then $3/month.
Does the trial need a credit card?
No. The trial is granted on first sign-in and is an entitlement on your account rather than a payment subscription, so there is nothing to cancel and nothing gets charged when it ends.
What happens when the trial ends?
The desktop app moves to a read-only state: your diagrams and settings are all still there, agent runs stop. The CLI keeps working, because it is free and separate.
Are there usage limits or metering?
No. Model usage is billed by whichever provider you choose, or costs nothing when you run locally, and never goes through Lucid Train. The desktop licence is a flat $3/month covering up to three devices.
Is the CLI really the same agent?
Same agent core, same models, same configuration file. The desktop app adds the diagram canvas, dependency audit, the Grafana surface, version history and a command palette.