Detective

Your modpack froze. Detective shows you what was happening.

Detective is a client-side diagnostic mod for Minecraft that records evidence around freezes and render-thread performance stalls, then helps you understand what was happening when the problem occurred.

Detect. Measure. Explain. Never accuse.

Detective does not simply name a mod and declare it responsible. It samples the render thread during a stall, preserves nearby performance history, ranks the strongest captured evidence, and clearly communicates when the result is ambiguous, insufficient, or potentially system-related.

Automatic freeze detection

Detective monitors active gameplay in the background and automatically records meaningful performance stalls using an adaptive detection threshold.

Black Box

Around every detected incident, Detective preserves roughly 30 seconds of nearby performance context, including frame-time history, JVM memory usage, dimension and player position. This makes it possible to see what was happening before, during and after a freeze.

Evidence-based attribution

When the captured evidence supports attribution, Detective can present a Primary Suspect together with technical evidence such as leaf ownership, stack presence and captured sample counts.

A Primary Suspect is not proof that a mod is defective or solely responsible. Configuration, game state, another mod, or an interaction between components may also matter.

Ambiguous Attribution

When multiple mods remain similarly plausible, Detective refuses to arbitrarily choose one. Instead, it reports an ambiguous attribution and shows the available evidence.

Modpack Changes

Detective compares recorded mod snapshots between launches and shows mods that were added, updated or removed, helping you investigate regressions after changing a pack.

Support Reports

Generate a lightweight local Support Report that can be shared with a mod developer or modpack author when troubleshooting.

Reports are created locally. Nothing is uploaded automatically.

Detective contains no telemetry, analytics, automatic uploads or remote API calls. Standard Support Reports do not automatically include latest.log.

Client-side only

Detective only needs to be installed on the client. Servers do not need Detective installed.

Requirements

Minecraft 1.21.1
NeoForge 21.1.235 or newer in the 21.1.x line
Java 21

NeoForge 21.1.248 is the recommended tested runtime.

Early Alpha

Detective's core detection, attribution, UI and Support Report systems have been validated, including a compatibility smoke test with 257 loaded mod IDs.

Long-duration validation on very large modpacks is still ongoing. Unexpected behavior is welcome feedback during this Early Alpha.

Privacy

Detective stores its diagnostic data locally. Review any Support Report before sharing it, just as you would any other diagnostic file.

Source & issue tracker

GitHub: https://github.com/blueez93/Detective

Detective finds the evidence. You make the call.