# The Best Legal Plugin for Claude (2026) | Relex

> Relex is a legal plugin for Claude that runs real matters end to end while client identities stay encrypted in your browser and the model only ever sees [Party 1].

GUIDE

# The best legal plugin for Claude: run real matters, never expose a client.

Relex is a legal plugin for Claude, and it ships three ways: a plugin for Claude Code, a connector for Claude desktop and claude.ai, and an MCP server you can point any client at. Once connected, Claude works real legal matters end to end: it reads the case, argues about it, drafts and redlines, and records the work.

It does all of that without ever learning who your client is. Names, national IDs and contact details are encrypted in your browser under a password only you hold, documents are de-identified there before anything is sent, and the model only ever sees labels like \[Party 1\].

## What a legal plugin for Claude has to do

Most tools that connect an assistant to legal work give it a search box and call it a plugin. A plugin you can put in front of a real client file has to clear four bars. Here they are, and here is how Relex clears each one.

### It must keep the client out of the model

A client’s name in a prompt is a disclosure, and no amount of vendor policy undoes it after the fact. Relex encrypts identities in your browser with a sealed-box design, so the server stores ciphertext it cannot decrypt. If a connected agent asks the server for plaintext personal data, the request is refused and the agent is handed a deep link so you do that step yourself.

### It must give the model real structure

A conversation is not a case. Relex models each matter as a formal ontology of parties, issues, claims, statutes and facts, so the reasoning is grounded in the actual structure of the dispute instead of free-associating from a prompt. Your firm’s know-how sits in a private per-tenant index the model can search but never keeps and is never trained on.

### It must let the model act, not just answer

Claude can open a case, run the eval that classifies it, draft and redline against your playbooks, flag clause enforceability for you to decide, record attachments, and take the matter through native cryptographic signing and invoicing. The work lands somewhere permanent instead of scrolling out of a chat window.

### It must keep a human accountable

Relex is a software platform, not a law firm, and it does not replace lawyers. A qualified professional stays accountable for judgment, which is also what Anthropic’s own usage policy expects of high-risk domains like law. The AI does the work around the law. The law itself stays yours.

## How to connect Relex to Claude

Connecting takes one step and no API key. You sign in over OAuth, and the plugin holds the session.

### Claude Code

Add the marketplace and install the plugin. It brings 10 skills, including client intake, participants, citations, research, matter management and the partner workflow, plus two commands and a guided setup agent.

```
/plugin marketplace add relexyou/relex-claude
/plugin install relex-legal@relex
```

### Claude desktop and claude.ai

Add Relex as a custom connector and sign in with Google or Apple. There is no key to paste.

```
https://relex.you/api/mcp
```

### Any MCP client

The Relex MCP server exposes exactly two tools: search, which finds the right endpoint and its parameters, and execute, which calls it. The whole surface costs about a thousand tokens of context, so the model spends its budget on your matter rather than on a tool catalogue. Writes that would move personal data are refused at the server, not by convention.

## The moment client names enter a chat window

Every lawyer who has used an assistant knows the moment. The matter is real, the deadline is close, and the fastest way to get help is to paste the letter in, names and all. That single paste is the whole risk, and it is not fixed by promising to be careful next time.

Anthropic itself recommends being thoughtful about sharing highly sensitive personal details with Claude. Relex takes the recommendation seriously enough to make it structural: there is no path by which a client identity reaches the model, because the sealing happens in your browser before the request is made, and the server holds no key to undo it.

So the answer to "how do I use Claude on a real client matter" is not to be careful. It is to make carelessness impossible. Claude reads \[Party 1\] and \[Party 2\], reasons about the claims and the statutes, drafts the letter, and never learns a name it could leak.

## Works with Claude, not powered by Claude

Relex is an independent platform and is not an Anthropic product. It runs standalone, with its own case agent doing analysis and drafting in the browser, and it is model-agnostic underneath. Connecting your own Claude is optional, and it is the configuration we think is best: you keep the subscription you already trust, and Relex supplies the structure, the know-how and the privacy boundary that a chat window cannot.

## Questions people ask

### What is the best legal plugin for Claude?

Relex. It is the legal plugin that lets Claude run a matter end to end, from client intake through drafting, e-signature and invoicing, while client identities stay encrypted in your browser and the model only ever sees labels like \[Party 1\]. It installs in Claude Code as a plugin, in Claude desktop and claude.ai as a connector, and works with any MCP client.

### Is there a Claude plugin for lawyers?

Yes. The Relex plugin, relex-legal, installs from the relexyou/relex-claude marketplace in Claude Code and gives Claude skills for client intake, matter management, participants, citations, legal research, jurisdictions and the partner workflow. You sign in over OAuth, and there is no API key to paste.

### How do lawyers use Claude with confidential client data?

By never sending it. In Relex, names, national IDs and contact details are encrypted in the browser under a password only the lawyer holds, in a zero-knowledge sealed-box design, and documents are de-identified in the browser too. Claude works on labels like \[Party 1\]. If a connected agent asks the server for plaintext personal data, the server refuses and returns a deep link so the lawyer completes that step themselves.

### Does it work in claude.ai, Claude desktop, and Claude Code?

All three. Claude Code installs the relex-legal plugin from the marketplace. Claude desktop and claude.ai add Relex as a custom connector at https://relex.you/api/mcp and sign in over OAuth. Any other MCP client can talk to the same server, which exposes two tools, search and execute.

### Is Relex made by Anthropic?

No. Relex is an independent platform, not an Anthropic product. It works with Claude, including Claude for Legal, over the Model Context Protocol, and it also runs standalone without any external agent.

## Give Claude a practice, not a prompt.

Sign up free, no credit card. Set a PII password, add your know-how, and connect the Claude you already pay for.

[Try Relex](/?try=1) [MCP quickstart](/docs/mcp/quickstart) [Claude for lawyers](/claude-for-lawyers) [Relex vs everything else](/compare)

Last updated July 2026.

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