Lexiel inside Claude and ChatGPT
https://api.lexiel.ai/mcpOAuth authentication with your Lexiel account. Nothing installed on your machine.
What you can do for free
40 queries a day, no credit card.
Search case law
Returns the exact paragraph to cite, from the verified corpus (CENDOJ, Constitutional Court, CJEU).
Verify citations
Checks any law or ruling against Spain's BOE and CENDOJ before it reaches your brief.
Audit a short brief
Flags every unconfirmed citation in a document up to 6,000 characters.
Search legislation
Finds the exact article in Spain's official gazettes.
- Full judgment text
- Long brief audits (no character limit)
- LO 1/2025 procedural compliance (competent court, MASC)
- Expanded search results (20 vs 5)
And so you never have to remember to ask: the plugin
The connector gives Claude access to the sources. The plugin tells it when to use them: 6 skills Claude invokes on its own when the matter fits, with nothing for you to remember. It covers checking whether a claim is admissible under LO 1/2025 before drafting it, auditing the citations in your brief or the other side's, and drafting the record that evidences the MASC attempt. Open source, Apache-2.0.
Install
claude plugin marketplace add codelabs-studio/lexiel-claude claude plugin install lexiel-es@lexiel
Or in the app: + → "Add plugins…" → paste the repository URL.
View the code on GitHubConnect it in under 3 minutes
Claude Desktop
- 1Open Claude Desktop → Settings → Connectors.
- 2Click "Add custom connector".
- 3Paste the URL above (https://api.lexiel.ai/mcp) and give it a name, e.g. "Lexiel".
- 4Authorize access with your Lexiel account when prompted (OAuth).
- 5Done: ask Claude to search case law or verify a citation.
ChatGPT
- 1Settings → Apps & connectors → Advanced settings → turn on Developer mode.
- 2Go back to Apps & connectors → "Create connector".
- 3Paste the URL above (https://api.lexiel.ai/mcp) and choose OAuth authentication.
- 4Authorize access with your Lexiel account.
- 5In every chat where you want to use it: "Add sources" → select Lexiel.
Steps verified as of August 2026; Claude and ChatGPT menu names may change over time.
Remote server with OAuth authentication (you never share your password with Claude or ChatGPT). Available tools depend on your plan; the free quota is shared at the account level and resets daily.
FAQ
What is the Model Context Protocol (MCP)?
MCP is an open standard (created by Anthropic, also adopted by OpenAI) that lets an AI assistant like Claude or ChatGPT connect to external tools and data in real time. In practice: it gives your AI access to Lexiel's verified legal corpus without leaving the conversation.
Do I need to install anything on my computer?
No. Lexiel's MCP server is remote (not local): you add a URL in Claude or ChatGPT's settings and authenticate with your Lexiel account (OAuth). There's no executable or server configuration involved.
What exactly counts as one query?
Every time your AI uses one of the tools, that is one query, however many results come back: if it returns ten rulings with their ECLI, that is one query, not ten. The 40 a day are a single shared counter across the four free tools (search case law, search legislation, verify a citation, audit a document's citations). A single question of yours can consume several if the model chains tools, for instance searching first and verifying afterwards.
What happens if I go over the 40 daily queries on the free plan?
The tool responds with a clear notice (never an opaque error) explaining that the daily quota is exhausted and which paid plan expands it. The quota resets every day at midnight.
Does it work the same in ChatGPT as in Claude?
The server and tools are the same; what changes is where you activate it. In Claude Desktop: Settings → Connectors → Add custom connector. In ChatGPT: Settings → Apps & connectors → Developer mode → Create Connector, then enable it per chat via "Add sources".
Is this the same as other free legal MCP connectors?
Not exactly. There are free legal MCP connectors focused only on searching and verifying rulings (for example Jurisprudenciator, at 30 queries a day plus a weekly bonus of 100; Lexiel gives 40 a day without that weekly bonus). Lexiel's difference is that the MCP is the entry point to a full platform: when you need to draft the brief, manage the case, invoice with VeriFactu or work across 19 other jurisdictions, you're already in the same account.
Ready to connect it?
Free account, no card. 40 queries a day.