Letra da Lei
Brazilian law in ChatGPT

Give your AI the letter of the law.

Describe what you need in ChatGPT or Claude and get Brazilian legal research, with cited sources, verified validity, and support drafting legal filings.

Install on ChatGPTInstall on Claude
See how it works
  • STF, STJ, TST, and more
  • Reviewable drafts
  • Brazil's first legal plugin in ChatGPT's app directory

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.

Available now

  • 205

    federal statutes indexed by article

  • 5

    federal case-law sources

  • 27

    states and the Federal District with indexed case law

How it works

Before the draft, the source.

No opening another site to type into a search box. You describe what you need in the assistant you already use, and Letra da Lei brings the right legal text, ready to research, support, and draft from official sources, without switching tools.

Built for the AI you already use

  • ChatGPT
  • Claude

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?
Today, ChatGPT and Claude (web and desktop). Letra da Lei is the first Brazilian legal plugin listed in ChatGPT's official app directory. Other MCP-compatible assistants should follow as they roll out 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.

Install on ChatGPTInstall on Claude