LEXA knowledge in the AI tools you already use.

Use your familiar AI tools — now with real legal background and citations.

The LEXA extension lets you connect ChatGPT and Claude Desktop directly to LEXA’s legal research engine. This means you do not need to switch between platforms: you ask your legal question where you already work.

🔌 Available extensions

💡 Why connect LEXA to the AI tool you already use?

General AI tools such as ChatGPT or Claude Desktop are extremely useful for drafting, summarizing and thinking. But there is one thing they are not reliable at: the current law of your country.

They do not know your national civil code in depth. They do not know what changed in labour law last year. They do not cite real court decisions. If you ask them a legal question without sources, the answer may be correct — but it may also be wrong, and you cannot easily tell which, nor verify it.

With the LEXA extension, this changes:

  • ChatGPT or Claude Desktop answers your legal question through LEXA’s database
  • Current legislation and real court decisions, with direct source references
  • No need to switch platforms: everything happens where you already work
  • Legal research becomes part of your usual workflow

In one sentence: The LEXA extension adds to ChatGPT and Claude Desktop what they do not have on their own — up-to-date knowledge of national and EU law.

📌 What can you use it for?

Legal research from the chat window

Ask ChatGPT / Claude directly: “What does case law say about excluding liability if the exclusion also covers intentional damage?” LEXA retrieves the relevant decisions, and ChatGPT / Claude summarizes them clearly.

Contract analysis with legal background

Upload a contract to ChatGPT / Claude and ask it to examine, using LEXA’s legal database, which current legal requirements apply to each clause. Processing long documents is one of ChatGPT / Claude’s strongest capabilities.

Drafting submissions, letters and legal summaries

ChatGPT / Claude drafts and writes, while LEXA ensures that legal references are current and accurate. You do not need to check separately whether a cited section is still in force.

Research by historical effective date (PRO)

Ask: “What was in force regarding this provision of the Civil Code on 1 June 2022?” LEXA retrieves the text in force at the appropriate historical date.

Compliance and policy checks

As in-house counsel, you can upload an internal policy, and ChatGPT / Claude — supported by LEXA — checks whether the document complies with current legal requirements.

🔎 Search modes

LEXA can perform searches in four ways. The ChatGPT / Claude application automatically selects the appropriate mode based on the question.

Searches returning relevant excerpts

1. Semantic search – meaning-based search across EU and national legislation, court and authority decisions, and professional sources. It returns the best-matching document excerpts and short summaries.

  • For legislation: it finds text passages most likely to provide the legal framework for the question.
  • For court decisions: it finds decisions most closely connected to the question from the perspective of facts or legal reasoning.

2. Title-based search – quotes and summarizes from a specific document based on the question, for example: “What does the Civil Code say about contractual penalties?”

3. Excerpt search by document identifier – deeper review of previously found documents: LEXA retrieves the document by identifier and returns further relevant excerpts and summaries from the previously found document.

Search returning a full document

4. Full search by document identifier – loads the full text of a previously found document into the ChatGPT / Claude context.

⚠️ Limitation. This mode works for documents up to approximately 250–300 pages. For longer documents, ChatGPT / Claude falls back to excerpt mode (3).

📦 Subscription and availability

The extension is available to Basic and Pro subscribers, currently free of charge as part of the existing subscription.

The integration is not available in the free START plan.

❓ Frequently asked questions

Are the extensions secure?

Yes. Authentication happens through the OAuth protocol and data traffic is encrypted. LEXA does not transfer data to AI applications — LEXA only returns the result of legal research to the chat session. For detailed information on data processing, please read our Privacy Notice.

Is use of the LEXA extension limited?

No. BASIC and PRO subscribers can use the extension without limits with both ChatGPT and Claude applications.

Do I need a paid ChatGPT or Claude subscription?

Yes, both AI applications require a paid subscription to use the LEXA extension.

For ChatGPT: Custom MCP extensions, including LEXA, are available with ChatGPT Plus, Pro, Business, Enterprise or Edu plans. Not with a free account.

For Claude: Custom MCP connectors, including LEXA, are available with Claude Pro, Max, Team or Enterprise plans. Not with a free account.

Does LEXA activate for every ChatGPT / Claude question?

No. ChatGPT / Claude decides whether the question requires a legal database query. LEXA does not activate for non-legal tasks. If you definitely want it to use LEXA, say so explicitly, for example: “Search with LEXA…”

What happens if LEXA does not find a relevant source?

LEXA cites only current, authoritative sources. If there is no exact legislative or court source, it says so — it does not guess.

What should I do if LEXA does not work properly?

Try the following:

  1. Restart the ChatGPT / Claude Desktop application.
  2. Log out and log back into LEXA at lexa-ai.eu.
  3. Remove the LEXA extension from the application, then reconnect it.

If the problem persists, contact the LEXA team: info@lexa-ai.eu