What is the maximum message size?

Ably is designed to be a realtime messaging platform that delivers small payloads incredibly quickly anywhere in the world.  As such, we have sensible defaults enforced on our accounts that encourages developers to use smaller payloads and deliver them as quickly as possible.  If you have a larger message size requirement, please raise a ticket and explain what message size you require along with an explanation and we'll do what we can to help.


Check how to measure your message size


Committed Use account message size limit

Configurable based on custom package for customer. The default for Committed Use accounts is 64kb, however theoretically this can be increased to 256kb based on each customer's use case.  Please get in touch to discuss your needs.


PAYG account message size limit (default)

64KB (65,536 bytes)


Free account message size limit (default)

16KB (16,384 bytes)


Please get in touch if you have any questions or are having any problems message size constraints. 


Please Note

  • The clientId and channel name are counted as part of the size of the message and will contribute towards the total message size.
  • If you are using the `publish(Array<Message>)` form to publish an array of messages, the message size limit applies to the sum of all messages in the array. As the messages in the array are published and broadcast atomically, they are treated as a single unit by our servers; the ability to represent them as into multiple separate messages is just a convenience.