Protocols / Binary Serialization
Enter one subscription filter and one published topic per line; choose the protocol version and delivery scenario.
Filter and topics are processed in this browser. No broker connection or network request is made.
Use + for one complete level and # only as the final complete level. A topic name cannot contain either wildcard.
One filter and up to 1,000 topic lines. Empty separator lines are skipped; spaces and empty topic levels are preserved.
Enter a filter and topics to begin.
An MQTT topic matcher helps when a device publishes successfully but a subscription sees nothing. A filter may differ by one level, case, leading slash or the special treatment of a $ system topic.
Paste the filter and a batch of actual topic names to compare the rule result with the retained-message delivery result. A matching rule does not always mean an existing retained message is replayed to a new MQTT 5 shared subscription.
A rule match and message delivery are separate questions.
The MQTT topic matcher marks where + consumes one level and where a final # covers its parent as well as descendants. Empty levels and $ system topics remain visible instead of being silently normalized.
A shared MQTT 5 filter can match a retained topic yet a new member receives no old retained copy. The report shows that difference for every topic while ordinary new subscriptions use Retain Handling 0.
Paste one filter and the published names exactly as sent. Case, spaces, leading slashes and empty levels are significant; blank separator lines alone are skipped.
MQTT 5 recognizes $share/group/filter; MQTT 3.1.1 treats those levels literally. Retained mode asks about old retained messages when a new subscription joins, not about future publishes.
A mismatch names its first differing level; a retained shared row distinguishes a matching filter from no initial replay. Export unlocks only when the result matches current inputs.
The MQTT wildcard tester applies + to one complete level and # only at the end, including a zero-level match of its parent. It does not reinterpret * or ? as wildcard operators.
Compare up to 1,000 topic names against one MQTT topic filter. Each row retains its original line number and explains the first mismatch; invalid names remain separate from ordinary misses.
MQTT 5 strips $share/group/ before matching; MQTT 3.1.1 keeps that prefix literal. The report never claims which member a broker will select.
No. + must occupy a complete level, and # must be a complete final level. A filter such as sensor/room+/temp is rejected with its column, rather than treated as a glob.
It matches exactly one level, including an empty level between slashes. Thus sensor/+ can match sensor/ but cannot match sensor without the slash.
# covers ordinary topics but excludes names beginning with $. Add an explicit $SYS/# filter on the broker. This page checks one filter at a time and shows the $ exception.
In MQTT 5, $share/group/filter uses the inner filter for matching, while shared subscriptions do not replay existing retained messages to a new member. Live matching messages may still go to one group member.
This MQTT topic matcher reports whether one filter matches each name; it cannot predict a broker's delivery count across multiple subscriptions, QoS settings or sessions. Test that behavior with your actual broker.
Still have a matching question?
Return to the MQTT topic matcher with a real filter and topic list; switch to retained mode only when testing an existing stored message for a new subscription.
All matching runs in your browser.