Relex & Claude vs CoCounsel
Own your clients, your data and your firm.
CoCounsel is Thomson Reuters’ legal AI assistant, positioned as fiduciary-grade AI for high-stakes professional work, and Thomson Reuters says its next generation is rebuilt on Anthropic’s Claude Agent SDK. So both Relex and CoCounsel meet Claude. The difference is what Claude is allowed to see, and who owns the client when the matter closes. In Relex, client identities never leave your browser, the model works on [Party 1], and the professional keeps the client and 100% of what they are paid.
At a glance
| Dimension | Relex | CoCounsel |
|---|---|---|
| Where client data goes | Encrypted in your browser before anything leaves your device. The model only ever sees [Party 1]. | States that user content and prompts are not used to train or improve CoCounsel or third-party LLMs, with zero-retention API calls to generative AI providers. |
| Whose AI runs it | Bring your own Claude or Claude for Legal over MCP and OAuth. You own the reasoning. | Thomson Reuters says the next generation of CoCounsel Legal is rebuilt on Anthropic’s Claude Agent SDK. Its MCP connector brings CoCounsel into Claude as a tool. It does not publicly describe bringing your own model into CoCounsel. |
| Try it today | Sign up and run a real case in minutes. Free to try, no card. | Contact sales. No public pricing. |
| Who owns the client | Partner Network: own the client and keep 100%, at 0% commission. | No client referral marketplace is publicly described. |
| Case structure | A formal ontology of parties, issues, claims, statutes, and facts. | Research, review and drafting skills across the Thomson Reuters ecosystem. |
| Your know-how | A private per-tenant index the model searches. Never a copy it keeps or trains on. | Thomson Reuters content and the documents you upload. |
| Getting started | In the browser in minutes, standalone or with your own Claude. | Sales process and onboarding. |
This comparison reflects each product’s own public positioning as of July 2026. CoCounsel is a trademark of its respective owner, and this page is an independent comparison.
The opposite bet
CoCounsel is the bet that legal AI is a research and drafting assistant you buy from the publisher who already owns the library, through a sales process, at a price neither of you will discuss in public. Relex takes the opposite bet. The AI is yours, brought in over an open protocol. The knowledge is yours, indexed privately and never trained on. The client is yours, and their identity is the one thing the model never gets.
Why the pairing wins
This is the comparison where the direction of the connection matters most. Thomson Reuters connects CoCounsel into Claude as a tool, so Claude can call it. Relex connects your Claude into your practice, so Claude runs the matter: it reads the ontology, searches your private know-how, drafts, redlines and records the work. And it does all of that against labels like [Party 1], because the real identities were sealed in your browser before anything was sent. The same model, the opposite architecture. One adds a research tool to your chat. The other gives your chat a practice, and refuses to hand it a single client’s name.
Own the intake, own the client
Clients reach your practice by email, by WhatsApp or SMS message, or through a guest link you send them, and what they tell you becomes a structured case the agent picks up without asking them to repeat it. Intake, drafting, native cryptographic e-signature and invoicing run in one workspace. Through the Partner Network you stay the merchant of record through Stripe, at a flat $99 per month and 0% commission on what your clients pay you.
Relex is a software platform. It is not a law firm, it does not replace lawyers, and it does not provide legal advice.
Questions people ask
Both use Claude. What actually differs?
What Claude sees, and which way the connection runs. Thomson Reuters describes an MCP connector that brings CoCounsel into Claude as a tool. Relex brings your Claude into your matters over MCP and OAuth, and it never sees a client identity: names, national IDs and contacts are encrypted in your browser, documents are de-identified there, and the model works on [Party 1].
What does CoCounsel cost?
Thomson Reuters does not publish pricing for CoCounsel; its plans page asks you to provide details and speak to sales. We do not repeat third-party estimates. Relex publishes its pricing live, and signing up is free with no credit card.
Is Relex a legal research tool?
Not primarily. Relex structures and runs the matter: the case ontology, your private know-how, drafting and redline, e-signature, invoicing and delivery, with a human professional accountable for judgment. It ships jurisdiction packs and a searchable index of United States local ordinances, and the reasoning is done by the model you connect.
Can I start without talking to anyone?
Yes. Sign up at relex.you in one click, with no credit card. Set a PII password, add your know-how, and run a case in the browser. To use your own Claude, install the plugin in Claude Code or add the connector in Claude desktop, and sign in over OAuth.
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