Controlling Tabstack Access

Tabstack is Mozilla’s developer-facing platform for programmatic, AI-driven interaction with web content. Website owners have clear visibility into automated access and straightforward mechanisms to control it.

This reference documents how Tabstack agents identify themselves, how exclusion signals are interpreted, and what behavior to expect when access is limited.

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Agent Identification

All requests originating from Tabstack include a dedicated User-Agent header that identifies the requesting agent.

User-Agent: Mozilla-Tabstack/1.0 (+https://tabstack.ai)

This identifier enables site owners to reliably recognize Tabstack traffic and apply access controls using standard web mechanisms.

Using robots.txt

Tabstack respects robots.txt directives that are explicitly addressed to its User-Agent.

Blocking All Access

To disallow Tabstack from accessing your site entirely:

User-agent: Mozilla-Tabstack
Disallow: /

Blocking Specific Paths

To disallow access to specific paths only:

User-agent: Mozilla-Tabstack
Disallow: /private/
Disallow: /admin/

When Tabstack detects a matching robots.txt rule, it will not fetch content from the disallowed paths.

Block Handling Semantics

When Tabstack is blocked via robots.txt:

Requests to disallowed paths stop immediately.

Requests fail fast rather than retrying repeatedly.

robots.txt results are cached to reduce follow-up requests.

This behavior minimizes unnecessary traffic and avoids repeated access attempts once an opt-out signal is detected.

Support and Feedback

If Tabstack traffic behaves unexpectedly, or if you have questions about access controls, contact: [email protected]

Feedback from website owners is welcomed, and Tabstack is operated with the intent to respect publisher preferences and support a healthier web.