Helix web agent

Helix is an AI coworker made by Neurastack. Each customer's Helix works on a cloud computer with its own web browser, and it does tasks the customer asks for from the Neurastack app, the web, or Neuraglass: comparing products, booking a table, filling in a form the person asked for, or reading a page to answer a question.

Helix is a user-directed browsing agent, not a crawler. It does not index the web, follow links in bulk, or collect content to train models. One operator (Neurastack) runs it for many signed-in people, so Cloudflare lists it as an intermediary agent.

• Only when a signed-in Neurastack customer has asked for something that involves your site.
• It opens the pages that task needs and stops when the task is done.
• It acts for that one person, with the sign-ins that person gave it.

Helix signs its requests with Web Bot Auth (HTTP Message Signatures, RFC 9421), the method Cloudflare uses to verify agents. Check the signature, not the IP address or user agent: Helix's browser is a standard Chrome, so its user agent is Chrome's.

Signature-Agent: "https://app.neurastack.com"
Signature-Input: sig1=("@authority" "signature-agent");created=...;expires=...;
                 keyid="<JWK thumbprint>";alg="ed25519";nonce="...";tag="web-bot-auth"
Signature: sig1=:<base64 signature>:

• Signature-Agent: https://app.neurastack.com
• Key directory: https://app.neurastack.com/.well-known/http-message-signatures-directory
• Algorithm: Ed25519. keyid is the key's JWK thumbprint (RFC 8037). Each signature is valid for 60 seconds.
• The key directory is itself signed (tag http-message-signatures-directory). When the key is rotated, the directory changes first.

A request that claims to be Helix without a valid signature for a key in that directory is not from Helix.

• robots.txt: Helix's server-side page reader obeys any group written for it by name (User-agent: Helix). Rules under User-agent: * are written for crawlers and are not applied to a person's own request, as with other user-directed agents.
• Site terms: Helix follows the instructions of the person it works for within your site's rules, and asks that person before anything that spends money, sends, posts, books or deletes.
• Human checks: Helix never completes a human check. The person always does. Helix never clicks, ticks, solves or otherwise completes a CAPTCHA, Turnstile, hCaptcha, reCAPTCHA or any "verify you are human" check, and it uses no solving services. When a page shows one, Helix stops acting on that page and hands it straight to the person, on their phone or on the computer, then waits for them. It never reloads or retries to get around a check.
• Sign-ins: Helix never types passwords or card numbers. It uses only sessions the person signed in to themselves, and it never tries lists of credentials.
• Rate: Helix opens only the pages a task needs, and its signing is rate-limited per person, so it browses at a person's pace rather than a crawler's.
• No disguise: with signing on, every request Helix's browser makes to your site carries the signature. It does not rotate identities or hide what it is.

• On Cloudflare: once Helix is verified it appears in Cloudflare's bot directory and can be allowed or blocked like other verified agents, in your bot settings or with a WAF custom rule.
• Anywhere else: verify the signature against the key directory above, then allow or block requests whose Signature-Agent is https://app.neurastack.com.
• With robots.txt, for Helix's page reader:

User-agent: Helix
Disallow: /members/

Or write to agents@neurastack.com and we will help. Blocking Helix only stops the agent; the person can still visit your site themselves.

Questions, a problem with Helix's traffic, or a request to be excluded: agents@neurastack.com. Please include your domain and, if you can, the time and the Signature-Input header of the request.