What is Bytespider and should you block it?
Bytespider is ByteDance's training crawler. Blocking it opts your pages out of model training and costs you nothing in search, as long as the file is written correctly.
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What Bytespider does
Bytespider is ByteDance's crawler (the company behind TikTok). ByteDance publishes no documentation for it, so what it collects and what the data is used for is not stated anywhere official.
On robots.txt: Bytespider behaviour is undocumented. Several site operators have reported that it keeps fetching after a robots.txt block, so treat the robots.txt line as a request and use a firewall rule if you need it stopped.
What blocking it costs
It costs nothing in search, if the file is written correctly. Blocking Bytespider tells ByteDance not to use your pages for training. It does not remove you from any search product.
The one way to lose search visibility while blocking Bytespider is a catch-all group that disallows everything. A crawler that is not named in the file falls into the catch-all, and that is how sites block OAI-SearchBot and PerplexityBot without meaning to.
How many of the top 5,000 sites block it
In my September 2026 census of the Tranco top 5,000, 2,771 sites returned a robots.txt. 542 of them block Bytespider (19.6%), which makes it the 2nd most-blocked of the 20 crawlers I checked. 463 files mention it by name; the rest of the mentions either allow it explicitly or restrict only part of the site.
For comparison, 699 sites (25.2%) block at least one training crawler, against 369 (13.3%) that block at least one AI search crawler. Most sites that opt out of training are doing it deliberately. Blocking AI search is more mixed, and skews more deliberate at large, recognizable sites than the rank alone would suggest: the breakdown is here. The full census is here.
The robots.txt lines
To block it:
User-agent: Bytespider Disallow: /
Keep the catch-all group permissive, or give the AI search crawlers their own groups, so this block does not take them down with it.
How to verify a request really came from Bytespider
There is no published address list, so a request claiming to be Bytespider cannot be verified.
No vendor documentation to link. Census: the September 2026 robots.txt census, raw data at /data/census.json.
All 20 crawlers. Check your own robots.txt against all of them with the checker.