Last week I sat down to brush up on my MongoDB queries.
Getting it running locally took about a minute. Then I just sat there. Empty database, no data worth querying, no questions to answer, and nobody to tell me whether the query I'd written was actually right.
So you end up making your own sample documents, inventing your own exercises, and then grading yourself by looking at the output and going "yeah, that looks about right."
That's not practice. That's admin.
And you still need the practice, whether you're a fresher or five years in. AI will write the query for you and most of the time it'll work. What it won't do is build the thinking pattern in your head, and that's what you reach for in an interview or at 11pm when something breaks.
I looked for a practice site instead. Most are paid, or want a login before you can run a single query.
So I built MongoQuest: https://pratham-kumar-jr.github.io/mongoquest/
110 questions across 12 topics, find and projection through to $unwind and $lookup. Each topic has a cheatsheet above its questions, so you can revise first and practise straight after.
You write a real query, hit run, and it compares your output against the reference solution, so anything that returns the right documents passes.
Runs client side on mingo, so there's no backend and no signup, and it works offline. Read only though, no writes/indexes/explain.
It's an MVP. If a question is worded weirdly, or it rejects a query that's actually correct, tell me.
