Letra da Lei
Legal research & drafting for AI

Give your AI the letter of the law.

We connect Claude, ChatGPT, Perplexity, and other AI assistants to Brazilian law so you can research statutes, cite articles, and draft legal filings with more confidence.

Get started for freeSee how it works
  • Official sources
  • Article & precedent citations
  • Reviewable drafts

The problem

Your AI doesn't know Brazilian law.

Ask an AI assistant about the IBS transition period for services under Brazil's Tax Reform. It may cite LC 214/2025 with confidence and still get it wrong. Even with web search the answer often comes not from the law itself, but from summaries and secondary sources.

Hallucinated citations

The AI cites a CDC article, but the number is wrong. The text sounds right, but the reference doesn't exist.

Yesterday's law

New laws take effect, regulations are published in the Official Gazette (Diario Oficial), and the AI has no reliable access to any of it.

Paying twice

Legal platforms now offer AI that generates content grounded in Brazilian law. But you're not canceling Claude just for that. You end up paying for both.

How it works

Before the draft, the source.

You stay in the assistant you already use. Letra da Lei brings in the legal text it needs to research, support, and draft from official sources.

Built for the AI you already use

  • Claude
  • ChatGPT
  • Gemini
  • Perplexity

Vision

More than federal law.

Today we cover federal legislation and federal and state case law. Next come the Diário Oficial, court-system integrations, and new workflows to make AI more useful and more reliable for legal work.

Available today

Federal legislation and case law, indexed at the article and the precedent.

Reliable retrieval, citation, and drafting support inside the assistants people already use.

What comes next

  • State and municipal legislation
  • Diário Oficial retrieval and monitoring
  • Court-system integrations (eSaj and others)
  • More AI assistants and drafting workflows

FAQ

What you're probably wondering.

How do I get started?
Add Letra da Lei to your assistant and sign in with Google. You can install it as a connector (works in any MCP-compatible assistant) or as a Claude plugin. Both are free. See the docs for the step-by-step.
What's the difference between the connector and the plugin?
Two ways to install. The connector gives your assistant the legal research and citation tools, and works in any MCP-compatible assistant. The Claude plugin installs the same connector plus the skills for drafting legal documents: petitions, defenses, appeals, and more.
Where does the data come from?
From official sources. We start with Planalto.gov.br, indexed at the article level with effective-date metadata. Third-party summaries are not our primary source.
Does it cover case law and state laws?
Federal and state case law are already live, alongside federal legislation indexed by article. State and municipal legislation are on the roadmap. See the coverage page for the full list.
Which AI assistants does it work with?
Any MCP-compatible assistant. Today that includes Claude (web and desktop); ChatGPT, Gemini, and others are rolling out MCP support.

Get started

Give your AI the letter of the law.

Add Letra da Lei to your assistant to research, cite, and draft legal documents grounded in Brazil's official sources.

Get started for free