A Sheets document with the best times for every track, plus statistics and rules for submission.
Times must be submitted in the Team Scripted Discord.
Time Attack leaderboard for custom tracks.
A Paper plug-in that allows you to save ghosts, watch replays, and race against staff ghosts.
(version 1.2.2, compatible with Sprint Racer v1.6.11)
A tool allowing you to transfer your Time Attack data and cheat codes between Sprint Racer worlds of any version. (Windows)
Here's the documentation on how to use the built-in track editor.
While making custom items is not fully supported, you can still put custom items on your tracks with some datapack knowledge. Sprint Racer has some partial functionality that lets you intercept item spawning, collection, and enchanting.
If you're planning to publish custom tracks, make sure the regions you want to use are available. This will help in avoiding file conflicts when people install your custom tracks.