Developer tools
LMQL: review, pricing, data and alternatives
LMQL lets developers write queries for language models and impose constraints on generated responses. It provides a visual environment for testing programs and inspecting the steps of generation. A free tier exists. Access and transparency score: 81/100, #2 of 31 in its category.
| Access | 15/30 | |
|---|---|---|
| Openness | 30/30 | |
| Trust | 36/40 |
What is LMQL?
LMQL lets developers write queries for language models and impose constraints on generated responses. It provides a visual environment for testing programs and inspecting the steps of generation.
According to its documentation, LMQL lets you:
- write queries for language models
- impose constraints on generated responses
- test programs in a visual environment
- use local models or remote services
- inspect generation steps
We file it under Developer tools, the category of tools to test, document and ship software, and it also overlaps with local LLM tools. The category lists 31 verified tools on this site.
The publisher is ETH Zurich, based in Switzerland. The service launched in 2023, which gives it some track record.
Who is it for?
It is mostly useful to these profiles: developers and researchers. The need it covers is simple to state: test, document and ship software.
LMQL is a good candidate if:
- you want to try before paying
- you plan to connect it to your tools or automations through its API
- you must keep your data in Europe or on your own machine
- you want to read the code or host it yourself
The best test is a concrete case from your daily work: if the tool does not beat your current method within a week, move on to an alternative.
How much does LMQL cost?
Pricing model: open source (public code). Basic use costs nothing.
To estimate what the same work would cost done directly with an AI model, use our API price calculator. Prices change often: always check the official site before subscribing.
Data and privacy
According to its privacy policy, data is processed on your device (local processing).
Local processing is the most favourable case: your files do not leave your machine for the features concerned.
Exporting your content: yes (details on the official site). Being able to get your data back makes switching tools easier later.
Three habits apply to every AI tool:
- turn off the use of your content for training if the option exists
- use a work account separate from your personal account
- review everything the tool produces before publishing or sending it
Platforms, languages and API
LMQL runs on: web browser, Linux, macOS, and Windows.
Interface languages: English.
A public API lets you call it from your own programs or an automation tool, and plug it into an AI agent.
The source code is public: lmql-langlmql-lang/lmql.
How we scored it
Our 81/100 score does not judge output quality: it measures what can be publicly verified about access to the tool, its openness and how far the publisher can be trusted.
| Criterion | Points | What counts |
|---|---|---|
| Access | 15/30 | free tier, published price, French interface |
| Openness | 30/30 | API, data export, open code |
| Trust | 36/40 | identified publisher, declared hosting, age, presence in reference lists |
The full calculation is explained on our method page.
Comparison with alternatives
LMQL against other tools in the developer tools category:
Verdict
LMQL is among the most accessible and transparent tools in its category.
Strengths
- Free tier to try it
- Public API
- Public source code
- Local processing available
- Established since 2023
Alternatives
Categories and jobs
Learn more
Frequently asked questions
Is LMQL free?
Yes, a free plan exists, with usage limits.
Where is LMQL data stored?
According to the publisher, on your device (local processing).
Does LMQL have an API?
Yes, a public API is documented.
What are the alternatives to LMQL?
In the same category: Firecrawl, Keploy, Jina Reader, and Metorial.
LMQL or Firecrawl: which one to choose?
Our score is 81/100 for LMQL and 83/100 for Firecrawl. Try both on the same task before paying.
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Neutrality. No affiliate links. No vendor pays to be reviewed, rated or ranked. Reviews are directed by François Chollet, neutral and factual, and every data point is dated and sourced. How we score