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Overview

When working with MQTT brokers that handle hundreds or thousands of topics, finding specific topics quickly is essential. MQTT Explorer’s search and filter feature provides instant, real-time filtering of the topic tree to help you locate exactly what you need. The search bar is always accessible in the top navigation: Location: Top center of the application interface Key Features
  • Real-time filtering as you type
  • Case-insensitive matching
  • Matches any part of the topic path
  • Clear button to reset filter
  • Works on mobile and desktop
The search bar is only available when you’re connected to an MQTT broker.
1

Start Typing

Click the search bar or just start typing (auto-focuses)
2

View Filtered Results

The topic tree updates instantly to show only matching topics
3

Select Topic

Click any filtered topic to view its details
4

Clear Filter

Click the X button or delete all text to show all topics again

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Auto-Focus Feature

For fastest access, the search bar auto-focuses when you start typing: Triggers Auto-Focus When:
  • You type any character (a-z, 0-9, etc.)
  • You press Backspace or Delete
  • No input field currently has focus
  • You’re not typing in a text editor or form
Won’t Auto-Focus When:
  • Typing in the Publish tab editor
  • Using keyboard shortcuts (Ctrl/Cmd + key)
  • An input field is already focused
No need to click the search bar first—just start typing from anywhere in the app to begin filtering!

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Filter Behavior

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Match Algorithm

The search filter uses intelligent matching: Partial Matching
  • Searches anywhere in the topic path
  • Example: temp matches:
    • home/living_room/temp
    • sensors/temperature/reading
    • temp_sensor/bedroom
Case-Insensitive
  • TEMP, temp, and Temp all match the same topics
  • No need to remember exact capitalization
Path-Aware
  • Matches across topic hierarchy levels
  • Example: home/temp matches home/bedroom/temp/current

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Preserved Hierarchy

Filtered results maintain topic structure: Parent Topics Included
  • Matching topics show their full parent hierarchy
  • Example: Searching sensor shows home/bedroom/sensor along with home and bedroom nodes
Tree Structure Maintained
  • Expand/collapse functionality still works
  • Topic relationships remain visible
  • Easy to understand context of matching topics
Before filter:
├─ home
│  ├─ bedroom
│  │  ├─ temp
│  │  └─ humidity
│  └─ kitchen
│     ├─ temp
│     └─ motion
└─ sensors
   └─ outdoor
      └─ temperature
After filter:
├─ home
│  ├─ bedroom
│  │  └─ temp          ← matched
│  └─ kitchen
│     └─ temp          ← matched
└─ sensors
   └─ outdoor
      └─ temperature    ← matched
On mobile devices, the search experience is optimized: Mobile Behavior
  • Tapping search bar automatically switches to Topics tab
  • Larger tap target for easier access
  • Font size prevents iOS zoom-on-focus
  • Touch-optimized keyboard appears
Mobile Viewport
  • Search bar adjusts width for smaller screens
  • Clear button always accessible
  • Results scroll smoothly
On mobile, the search bar may appear smaller but expands when focused for comfortable typing.

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Keyboard Shortcuts

Navigate filtered results efficiently:
KeyAction
Start TypingAuto-focus search bar
EscapeClear search and blur input
BackspaceDelete characters (auto-focuses if not in field)
↓ / ↑Navigate through filtered topics
EnterSelect highlighted topic
Combine search with keyboard navigation: Type to filter, then use arrow keys to quickly browse results.

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Performance with Large Topic Sets

The search filter is optimized for performance: Efficient Filtering
  • Operates on topic paths (not message payloads)
  • Incremental filtering as you type
  • No lag even with 10,000+ topics
  • Lightweight string matching algorithm
Optimized Rendering
  • Only renders visible filtered nodes
  • Collapsed nodes don’t render children
  • Smooth scrolling with large result sets

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Search Use Cases

Find Device Topics

Search for specific device IDs or names across your broker

Locate Sensor Types

Find all temperature, humidity, or motion sensors quickly

Debug Specific Paths

Isolate problematic topics during troubleshooting

Filter by Room/Zone

Show only topics for a specific room, floor, or building

Identify Wildcards

Search for topics matching a pattern before subscribing

Audit Topics

Review topics containing specific keywords for compliance

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Filter Tips & Tricks

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Search Strategies

If your topics include device IDs (e.g., device/abc123/status), search for the ID directly:
Search: abc123
Find all topics of a specific type:
Search: temperature
Search: /status
Search: /cmd
Filter topics by location hierarchy:
Search: bedroom
Search: floor1
Search: building_a

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Naming Conventions for Searchability

Design topic hierarchies with search in mind: Good Topic Structure 
✅ location/room/device_type/metric
   home/bedroom/temp_sensor/value
   
✅ organization/site/building/floor/device_id
   acme/factory1/building_a/floor_2/sensor_001
   
✅ device_id/function/command
   device_abc123/light/set
Searchable Patterns
  • Include device IDs in topic paths
  • Use consistent naming for similar devices
  • Add descriptive suffixes (/status, /cmd, /data)
  • Include location identifiers
Avoid using generic terms only (like data, value, state) without context, as they’ll match too many topics.

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Clear Filter

Return to full topic view: Methods to Clear
  1. Click the X button in the search bar
  2. Delete all text manually
  3. Press Escape while search is focused
After Clearing
  • All topics become visible again
  • Tree expansion states are preserved
  • Selected topic remains selected

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Search vs Subscribe Wildcards

Understand the difference:

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Search Filter

  • Client-side filtering of received topics
  • Filters what you see in the tree
  • Does not affect subscription or data received
  • Instant, no network traffic

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Subscribe Wildcards

  • Server-side filtering of which messages to receive
  • Controls what data the broker sends to you
  • Uses MQTT wildcards (+ for single level, # for multi-level)
  • Configured in connection settings
Use subscribe wildcards to limit incoming data, then use search to filter your view of that data.

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Accessibility

Screen Reader Support
  • Search bar labeled as role="search"
  • Input labeled with aria-label="Search topics"
  • Result count announced (when implemented)
Keyboard-Only Navigation
  • Fully operable without mouse
  • Clear visual focus indicators
  • Standard keyboard shortcuts

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Best Practices

Use Specific Terms

Search for unique identifiers rather than generic terms

Clear Between Searches

Clear filter between different searches to avoid confusion

Combine with Tree Navigation

Filter to narrow results, then use arrow keys to browse

Save Common Searches

Keep a list of common search terms for your specific setup

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