Debug Block Collision Overlay Reloaded
Debug Block Collision Overlay Reloaded adds an F3 debug overlay that shows exact block collision shapes for Minecraft 1.12.2 on Forge.
What it does
Standing near blocks with the debug screen open, a player sees the precise collision boxes that the game uses for each block, which helps when a shape does not match what the eye expects. The overlay is a client-side addition, so only the player's installation needs it, and a server running vanilla or another setup can stay untouched. The mod is published for Forge only, with its latest file, 2.1.1, dated 2026-02-04.
The overlay behaviour is set in a config file, where the mode, the chat feedback line and the rendering options can be changed. The same settings can also be adjusted in game through Forge's configuration screen, and changes are applied without restarting the client. Cleanroom Loader 0.4.2-alpha Celeritas was the setup used for testing this build. The project is released under The Unlicense, so it is open source, and the source code and issue tracker are public.
Key features
Collision box overlay
The F3 debug screen gains a display of the exact collision shape of the block being looked at.
Adjustable display modes
Overlay mode and level can be set so the collision information shows only as much detail as needed.
Chat feedback line
An optional line in chat reports changes and state, which can be turned off in the config.
Live config reload
Settings edited in the config file or the in-game configuration screen take effect without restarting the game.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Who it’s for: The mod suits players and map makers on Forge 1.12.2 who need to inspect block collision details. Server owners do not need to install it, since only the client runs the overlay.
How it compares
Memory Display is a Fabric, Forge and NeoForge client overlay for version 1.21, licensed under the GNU Lesser General Public License v3.0 or later, and it shows memory use rather than collisions. REI Clean Overlay is a client-side Forge mod for 1.20.1 under the MIT License, but it is not open source in the project's own terms and it is not a collision tool. Create Stress Debug is a Forge mod for 1.20.1 – 1.20.6 that runs on both client and server and is open source under the MIT License, which means it has to be installed on every player's side and the server as well.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Debug Block Collision Overlay Reloaded | Forge | 1.12.2 | Client-side only | 2026-02-04 |
| Memory Display | Fabric, Forge and NeoForge | 1.21 | Client-side only | 2024-11-08 |
| REI Clean Overlay | Forge | 1.20.1 | Client-side only | 2026-06-29 |
| Create Stress Debug | Forge | 1.20.1 – 1.20.6 | Client and server | 2024-11-22 |
Questions
Does Debug Block Collision Overlay Reloaded need a server install?
Which loader and game version does the mod target?
Can the settings be changed without restarting the game?
In the catalog
Debug Block Collision Overlay Reloaded is one of 36,990 Utility mods on ModsFinder, and one of 14,575 Utility mods for Forge. 2,920 mods support Minecraft 1.12.2.
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What the author says
A client-side mod that adds a new F3 debug overlay showing you exact block collisions. There is also a config file which is dynamicly reloaded and can be edited in game or on the main menu.
Official listing
- Modrinth page
- modrinth.com/mod/debug-block-collision-reloaded
- Owner
- barnabeepickle
- Published
- 2026-01-30
- Updated on Modrinth
- 2026-02-04
- Facts verified
- 2026-10-15