1) You can use Sleepy Mongoose “sleepy.mongoose is a REST interface for MongoDB.” For that you would need to be running your own MongoDB instance.
2) If you don’t mind hosting your MongoDB somewhere else; MongoLab is a great host (provides 240MB for free) (other hosting options); it provides a nice REST API (in addition to a nice administration UI):
MongoLab’s API exposes most the operations you would find in the MongoDB driver, but offers them as a RESTful interface over HTTPS. Documentation is here.
keywords: JSON MongoDB REST RESTful API mongodb rest api