Providers may offer third-party services, external to the Block Protocol, which blocks can reach out to and utilize, to provide additional or improved functionality.
Example services include the OpenAI ChatGPT APIs, also known as GPT-3.5 Turbo, GPT-4 and GPT-4.5 Turbo.
The Block Protocol defines a standardized way for blocks to access external services. If an embedding application directly integrates with that service, it can take over handling of the request. If it does not, the block will fall back to processing the request via the Block Protocol itself, which supports a number of different services. These include many of OpenAI and Mapbox's public current public APIs.
All supported services will soon be listed on the Þ Hub, allowing for easier discovery.
If you want to access a particular service in the block, reach out on Discord to check it doesn't already exist, or contact us to request it be added. We'd love to learn more about your use case!
A number of limitations apply to the use of services in blocks.
Most services are rate-limited, to varying degrees. Block Protocol API key and user account rate limits will be published soon. Service (e.g. GPT-3.5 Turbo) and where applicable provider (e.g. OpenAI) rate limits will be listed on the relevant service listing pages once live.
By attempting to access services via blocks, you agree to adhere to the original provider's terms of service, as outlined in the Block Protocol Terms for Additional Products and Features.