We are thrilled to announce that NATS Server 2.11 is finally here!

We want to extend a heartfelt thank you to everyone who contributed through discussions, issue reporting, code contributions, and testing early versions. ❤️

A Long Journey to 2.11

The 2.10.x series was our longest yet, having currently reached 26 patch releases. Throughout this extended period, our ongoing commitment to testing and quality assurance delivered excellent results, making 2.10.26 the most stable and reliable release to date.

Thanks to our on-going partnership with Antithesis , and significant time and resources invested in our internal testing infrastructure with numerous chaos tests running nightly, we were able to effectively identify and resolve bugs and rare issues—those one-in-a-million occurrences—that are typically very difficult to reproduce under normal conditions. You can read more about it in Antithesis blog post

Additionally, we’ve increased our focus on documenting the Architecture and Design of new features.

These enhancements significantly extended our release cycle, but we firmly believe the extra effort was worthwhile.

What’s New in 2.11

The latest release brings several important features requested by our customers and the community. While we won’t cover every change here, we’ll highlight the most impactful ones:

Single Message TTL

Design document

This highly anticipated feature allows users to set a TTL for individual messages.

It also enables receiving Delete Markers on Stream for messages that reached MaxAge. This is a big step in improving our Key Value Stores by being able to get notifications about expired keys and will be adopted by our clients in the near future.

Consumer Pinning and Overflow

Design document

Another frequently requested feature, built on top of the new Consumer Priority Groups, which we plan to expand further in future releases. For now, users can leverage two powerful options:

Pinning a Consumer to a Specific Client

When you want only one client or application to receive messages from a consumer without sacrificing High Availability, consumer pinning solves this elegantly. It ensures only one client actively receives messages while others remain in standby mode. If the active client disconnects or encounters an issue, a standby client seamlessly takes over.

Overflow

It’s often beneficial to prioritize message consumption by clients local to a consumer’s cluster node—whether due to latency (RTT) concerns or cost efficiency related to cross-AZ or cross-region traffic. However, when local clients become overloaded, the Overflow feature allows messages to spill over to remote clients. Users can configure a threshold based on pending acknowledgments or messages, activating overflow handling automatically when necessary.

Consumer Pause

Operators and developers occasionally need to temporarily halt message consumption—for maintenance, debugging, or other reasons. Consumer Pause allows pausing the delivery of messages to any client until a specified deadline.

Distributed Message Tracing

Design document

Tracing in distributed systems is essential yet notoriously complex. NATS Distributed Message Tracing simplifies this process significantly. By specifying a simple header in messages, you can now trace messages throughout your entire NATS topology—including gateways, leafnodes, imports and exports — providing invaluable insights, especially within complex cluster and supercluster arrangements.

Multi Message Get

Design document

Since NATS Server 2.8, retrieving specific messages from streams using various filters has been a foundational feature, notably underpinning our KV stores. The new 2.11 release expands this capability, enabling batch retrieval of messages. This offers a vastly more efficient approach to processing streams without the overhead of creating dedicated consumers or fetching messages individually.

Summary

NATS Server 2.11 includes numerous additional features and enhancements beyond those outlined here. For a complete overview, please consult the full Changelog .

Additionally, review the version 2.11 documentation and upgrade guide here .