Amazon SNS 1 MiB Payloads Make 256 KiB a Compatibility Boundary
Cover image: Amazon SNS payload-size compatibility map showing the default 256 KiB boundary, the opt-in 1 MiB ceiling, and the restricted SQS, Lambda, and Data Firehose path above 256 KiB. Original illustration: Tech Trend Insight. Miles Park IT engineer and technology analyst based in Virginia. About the author AWS expanded Amazon Simple Notification Service payloads on September 19, 2026 , from 256 KiB to a configurable maximum of 1 MiB (1,048,576 bytes) for Standard and FIFO topics. The feature is opt-in through the MaximumMessageSize topic attribute; existing and newly created topics remain at 256 KiB (262,144 bytes) unless that attribute is set. ( AWS announcement , AWS 2026 announcement archive ) The consequential boundary is not 1 MiB, however. It is 256 KiB . Configuring a topic above that threshold restricts which endpoints may subscribe, limits the topic to 100 subscriptions, creates a size mismatch with Amazon Data Firehose, and changes the cost profile of large me...