🔍 Diagnostics & Tools · Minecraft Mod · Forge / Fabric / NeoForge · 1.16.5 – 1.21+
Profiler · Flame graphs · TPS & memory diagnostics
Spark is the profiler you reach for when a modpack drops to 12 TPS and nobody knows why. It samples the server or client thread, produces a shareable interactive call-tree, and pairs it with memory inspection and tick-health reporting — turning guesswork into a screenshot of the exact method eating your frame budget.
- Low-overhead sampling profiler for both client and server threads
- Uploads results to a shareable interactive flame-graph viewer
- Memory inspection: heap summary, GC activity and object counts
- Tick health monitoring with TPS and MSPT history
- Works on Forge, Fabric, NeoForge, Paper, Spigot and Fabric servers
| Version | Compatibility | Download |
|---|---|---|
Spark-Legacy.jar |
Forge 1.16.5 – 1.17 |  |
Spark-Modern.jar |
Forge / Fabric / NeoForge 1.18 – 1.21+ |  |
Direct links
- Spark-Legacy.jar — Forge, Minecraft 1.16.5 and 1.17
- Spark-Modern.jar — Forge / Fabric / NeoForge, Minecraft 1.18 through 1.21+
- Download the JAR matching your Minecraft version from the table above.
- Install a mod loader — Forge, Fabric or NeoForge for your exact game version.
- Place the
.jarinto your.minecraft/mods/folder (create it if it is missing). - Launch Minecraft using the modded profile.
- Verify Spark appears in the in-game mods list.
Tip: if the game crashes on startup, you almost certainly mixed a Legacy JAR with a Modern Minecraft version, or are missing a required dependency. Check
latest.logfirst.
| Build | Loader | Minecraft Versions |
|---|---|---|
| Legacy | Forge | 1.16.5, 1.17 |
| Modern | Forge / Fabric / NeoForge | 1.18, 1.19, 1.20, 1.21+ |
Q: How do I start a profile? A: Run /spark profiler start, play for a minute or two, then /spark profiler stop for a link.
Q: Does profiling itself cause lag? A: Sampling overhead is small by design — it is safe to run briefly on a live server.
Q: Can I use it to find a laggy mod? A: That is its main use: the call tree names the exact mod package consuming tick time.
Q: Is it safe to add to an existing world? A: Yes in most cases — back the save up first, as you should with any mod addition.
Q: Can I use it in a public modpack? A: Yes. Both builds are modpack-ready and require no additional setup.
Spark · Diagnostics & Tools · Minecraft Mod
Legacy (1.16.5 – 1.17) and Modern (1.18 – 1.21+) builds available in every release.