Harun Seyhan highlights an API change aimed at developers working with large requests: Anthropic increased the maximum request size for the Messages API and Token Counting API from 32 MB to 128 MB. The official Claude Platform release notes date the change to October 28, 2026.
Four times the request-body capacity
The release notes specify the first-party Claude API. The new ceiling concerns the size of the request sent to those endpoints. The channel points to image-heavy requests, extended computer-use sessions and large PDFs as examples where the former byte limit could be reached while token context remained available.
The increase gives those requests more space without redefining the model’s token-based context window. These are different limits: a request’s encoded data size and the amount of context a model can process do not measure the same thing.
The change is endpoint-specific
Anthropic’s current API error documentation lists 128 MB for both Messages and Token Counting. It separately lists 256 MB for the Batch API and 500 MB for the Files API.
Requests exceeding the applicable ceiling return a 413 request-too-large error. The documented change does not establish identical limits for every third-party platform hosting Claude; its stated scope is Anthropic’s own API.
