MQTT Topic Tester

Online MQTT topic tester with + and # wildcard validation and subscription filter matching, ideal for protocol learning, topic design review, and message routing debugging.

Subscription Pattern

Use + for single-level wildcard and # for multi-level wildcard (must appear at the end)

Test Topics

One topic per line. Test topics represent publish topics and cannot include + or #

Common Patterns

Results

Enter subscription pattern and test topics to start

Matched

Not matched

Wildcard Reference

`+`Single-level Wildcard

+ matches exactly one topic level and cannot span across levels.

`#`Multi-level Wildcard

# matches all remaining levels from its position and must be the last token.

Documentation

What is MQTT Topic Matcher Tester

This tool verifies whether topics match a subscription pattern, focusing on wildcard behavior of + and #.

Key Features

Validate subscription pattern syntax.
Batch-test multiple topics at once.
Show per-segment match visualization.
Provide quick patterns and one-click examples.

Steps

Enter a subscription pattern.
Input test topics line by line.
Review match results and mismatch reasons.

FAQ

Why must `#` be the last level?

Per MQTT spec, # is a multi-level wildcard and must appear at the end of a filter.

Can publish topics contain wildcards?

Normally no. Wildcards are intended for subscriptions, not publish topic names.