MongoDB vs Apache Cassandra
MongoDB is a document database sold mostly as a priced cloud service. Apache Cassandra is a masterless wide-column database that nobody sells: the code is free under Apache License 2.0 and the cost is the people who run several nodes. Cassandra's query language has no joins or sub-queries, so you shape tables around queries up front.
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Choose MongoDB ifyou want a managed service with a free cluster, published hourly prices and a vendor to contact.
Choose Apache Cassandra ifyou write very large volumes across several machines or data centres and have staff to operate the cluster yourself.
MongoDB and Apache Cassandra side by side
| MongoDB | Apache Cassandra | |
|---|---|---|
| Our database management system rank | #5 of 19 | #7 of 19 |
| Established in | United States | United States |
| List price, 2 November 2026 | Billed hourly. Dedicated: 10 GB to 4 TB, from $56.94 monthly. Flex: 5 GB, capped near $30 monthly. Free: a 512 MB Atlas cluster | Free under Apache License 2.0; no vendor sells it |
| Free tier | Yes | Yes |
| Open source | — | Yes |
| Self-hostable | — | — |
| Built for | Teams building around JSON documents who prefer a managed cloud service | Teams writing very large volumes across data centres, with staff to operate it |
| Not for | Buyers who need an OSI-approved licence for the server | Small applications needing joins and a single inexpensive server |
Both are reviewed in full in our database management system ranking: MongoDB and Apache Cassandra.
Where they differ
MongoDB 2 · Apache Cassandra 2 · open 1- 01
Getting started cheaply
On Atlas you get a free 512 MB cluster, plus a 5 GB Flex step whose bill tops out at $30 per month. Cassandra has no plan at all and its home page shows no commercial price, but the project states there is little point in running a single node. A small trial is simpler on Atlas.
Edge: MongoDB
- 02
Licence and who sells it
Cassandra is under Apache License 2.0, published by the Apache Software Foundation, a 501(c)(3) non-profit. The SSPL covering MongoDB's server was drafted by MongoDB itself, and it obliges you to release service source code if third parties use the program as a hosted service. Cassandra's terms are the plainer of the two.
Edge: Apache Cassandra
- 03
Growing capacity
Cassandra's masterless design lets you add or remove nodes with no downtime, per the project. Hourly billing applies to MongoDB Dedicated clusters sized 10 GB through 4 TB, and Search or Stream Processing carry their own prices. Cassandra's growth is a hardware and staffing choice, not a rising list price.
Edge: Apache Cassandra
- 04
Querying
Cassandra's CQL does not execute joins or sub-queries, and each select statement applies to a single table, so models are built per query. We found no equivalent limit stated on the MongoDB pages we read, but we also have no MongoDB query documentation to compare, so we call this even.
Depends on the buyer
- 05
Support route
MongoDB has one company behind it, and Enterprise Advanced offers self-managed use under a commercial licence with sales-only pricing. Cassandra's project sells nothing, so support is whatever you arrange yourself. For a team without database specialists, MongoDB offers the clearer route.
Edge: MongoDB
When neither fits
If you need joins and one inexpensive server, a relational engine such as PostgreSQL or MariaDB is a better fit than either.
MongoDB or Apache Cassandra: questions
3 answersIs Cassandra free?
Yes. It is licensed under Apache License 2.0 and the project home page shows no commercial price or plan. Your cost is the machines and the staff to run several nodes.
Does Cassandra support joins?
No. The CQL documentation states it does not execute joins or sub-queries, and a select applies to a single table.
What is the current Cassandra release?
The download page lists 5.0 as latest GA (5.0.9) and 4.1 as previous stable (4.1.12), with releases dated 2026-08-07.
Sources
Checked 2 November 2026- MongoDB pricing page: Atlas tiers, extra service prices, sales-only Enterprise Advanced.
- MongoDB Server Side Public License: who wrote the SSPL, its source code duty.
- Cassandra basics: masterless, little point in one node, add or remove nodes without downtime.
- Cassandra downloads: Apache License 2.0, release versions and dates.
- Cassandra CQL DML: no joins or sub-queries, select on a single table.
- Apache Software Foundation: 501(c)(3) non-profit.
- Cassandra home: no commercial price or plan.