Redis and MongoDB both are open-source NoSQL databases. Both are similar in many ways. For example: Both are released in 2009. Both are NoSQL database. Both are getting popular day by day but there are some differences between them.
||Redis is faster than MongoDB (when the stored data is small) but the API is very "atomic".
||MongoDB uses more resources so it is comparatively slow but the API is extremely easy to use.
||It is hard to code in Redis database.
||Coding is easy in MongoDB database.
||Redis is a key value storage.
||MongoDB is a document type storage.
||Redis is not as reliable as MongoDB. It is stable from version 2.4.
||MongoDB is more reliable than Redis.
||Redis database doesn't follow the conventional pattern. It is a key value storage.
||MongoDB is relatively more conventional. It follows document oriented structure.
||Redis database is preferred when the data is not changing over the time and accessed very often.
||Otherwise MongoDB is preferred.
||In Redis database, query is possible only by key.
||Indexing is possible in MongoDB so query can be done by key or by any value in the document.
||Redis is developed by Salvatore Sanfilippo.
||MongoDb is developed by MongoDB Inc.
||Redis is written and implemented in C language.
||MongoDB is written and implemented in C++.
||Redis database can be used as a cache.
||MongoDB is a persistent database.