MongoQuest – practise MongoDB queries in your browser

110 hands-on exercises across 12 topics, a cheatsheet for each one, and a query runner that checks your answer. Everything runs locally in your browser.

Topics covered

• Finding & Projection – find, findOne, picking fields, counting, distinct.
• Comparison Operators – $gt, $lt, $gte, $lte, $ne, $in, $nin, $mod.
• Logical Operators – $and, $or, $not, $nor – and when you don't need them.
• Element & Type – $exists and $type – schema questions on schemaless data.
• Pattern Matching – $regex – starts with, ends with, contains, case-insensitive.
• Sort, Limit & Skip – Ordering results and paginating them.
• Array Queries – $all, $size, $elemMatch, positional dot paths.
• Embedded Documents – Dot notation into nested objects and arrays of objects.
• Aggregation Basics – $match, $project, $addFields, $count, $sort, $limit.
• Grouping & Accumulators – $group with $sum, $avg, $min, $max, $push, $addToSet.
• $unwind & Array Pipelines – Flattening arrays so you can group across their elements.
• Joins & Advanced Stages – $lookup, $facet, $bucket, $replaceRoot, $graphLookup, top-N per group.