Cassandra vs ScyllaDB

Quick verdict

Apache Cassandra is a distributed wide-column database from the Apache Software Foundation. Tables are defined by a partition key, which decides which nodes hold a row, and clustering columns that order rows within a partition; every node can serve reads and writes, and the client chooses a consistency level per request. Cassandra 5.0 became GA on 5 September 2024, and 5.0.9 (7 August 2026) is the latest release, with 4.1 and 4.0 still maintained. It is free under the Apache License 2.0. See our Apache Cassandra profile.

ScyllaDB is a distributed wide-column database from ScyllaDB, Inc. that speaks CQL, so Cassandra drivers and data models carry over, and also offers Alternator, an Amazon DynamoDB-compatible API. It is written in C++ and splits each node's data by CPU core. Recent releases use tablets for data distribution (recommended for all new clusters from 2026.1) and Raft for cluster metadata; 2026.3 was announced on 8 September 2026. See our ScyllaDB profile.

Side by side

Key differences

Licence: open source versus source-available with limits

This is the biggest change in the comparison since 2024. Cassandra is Apache 2.0: you can run it at any scale, modify it, offer it as a service and buy support or hosting from whichever vendor you like. ScyllaDB's current licence (v1.1, 12 April 2026) grants free use only to "Never Customers", meaning organisations with no paid relationship with ScyllaDB in the previous 12 months, and only up to 10 TB of total storage and 50 vCPUs across all clusters. It also assigns modifications to ScyllaDB, allows audits, licence keys and telemetry, forbids offering ScyllaDB as a service, and is governed by Israeli law.

In practice, a small self-managed ScyllaDB cluster may run free, but a growing one, or any organisation that has ever paid for ScyllaDB in the past year, needs a commercial licence or X Cloud. Have your legal team read the licence before you choose, and plan what happens when you cross the limits.

Engine design and data distribution

Cassandra is written in Java and places data on a token ring by hashing the partition key, with replicas per data centre. Version 5.0 modernised the storage engine with trie-based memtables and SSTables and the Unified Compaction Strategy.

ScyllaDB reimplements the same model in C++ and splits each node's data by CPU core, so each core owns its own slice of data. It now distributes data with tablets, smaller units that the cluster can move between nodes, recommended for all new clusters from 2026.1, and uses Raft for cluster metadata. ScyllaDB publishes performance comparisons; they are vendor claims, and we do not repeat them. Run your own workload if throughput or latency per node is the reason you are looking.

Compatibility: what carries over from Cassandra

Both use CQL, so schemas, queries and drivers look the same:

-- CQL: runs on Apache Cassandra and ScyllaDB
CREATE KEYSPACE telemetry
  WITH replication = {'class': 'NetworkTopologyStrategy', 'dc1': 3};

CREATE TABLE telemetry.readings (
  device_id text,
  day       date,
  ts        timestamp,
  value     double,
  PRIMARY KEY ((device_id, day), ts)
) WITH CLUSTERING ORDER BY (ts DESC);

SELECT ts, value FROM telemetry.readings
WHERE device_id = 'd-42' AND day = '2026-11-07' LIMIT 100;

The baseline differs, though. ScyllaDB's compatibility page describes it as a drop-in replacement for Cassandra 3.11, with additional features from 4.0, CQL native protocol v4 and some v5 features, and tools based on 3.11. It no longer supports Thrift (from ScyllaDB 6.0), does not support DateTieredCompactionStrategy (use TWCS), ignores some table options, marks user-defined functions as experimental, and rewrites Storage Attached Index definitions on vector columns to its native vector index. If you rely on Cassandra 4.x or 5.0 features, check each one on that page before migrating.

APIs, search and vectors

ScyllaDB adds Alternator, a DynamoDB-compatible API on the same cluster, which lets DynamoDB-style applications run outside AWS. Its 2026.3 release added full-text search over text columns with BM25 scoring, large-data guardrails and cluster-wide restore, and it offers vector search.

Cassandra 5.0 added Storage Attached Indexes (SAI), a vector data type with similarity functions, dynamic data masking, a CIDR authorizer and more guardrails. It has no DynamoDB API; Amazon Keyspaces is AWS's CQL-compatible service, which is not Apache Cassandra itself.

Operations, support and managed options

With Cassandra you operate the cluster (repair, compaction, capacity planning) or choose among third-party managed services and support vendors, such as DataStax Astra DB (now part of IBM) or Amazon Keyspaces, each with its own compatibility and pricing. The project itself sells nothing.

ScyllaDB ships companion tools (ScyllaDB Manager, the Monitoring Stack and a Kubernetes Operator) and runs ScyllaDB X Cloud, billed on demand by the hour or on 1-year or 3-year subscriptions with prepaid Flex Credits. One vendor for software, support and hosting is simpler to buy, but it also means a single supplier and licence holder for your data layer.

Pricing and licensing

Apache Cassandra is free under the Apache License 2.0, with no paid edition from the project. Costs are your own infrastructure and operations, or third-party managed services and support, each priced by its own vendor.

ScyllaDB. Self-managed use is free under the licence only for organisations that have not been paying customers in the previous 12 months, up to 10 TB of total storage and 50 vCPUs; beyond that a commercial licence is required, priced by quote. ScyllaDB X Cloud publishes no rates on scylladb.com/pricing (checked 7 November 2026): it is billed by instance type, storage, plan and deployment model, on demand by the hour or by 1-year or 3-year subscription with Flex Credits, plus cloud network and backup costs. The page offers a calculator, a 30-day developer trial and a 48-hour production evaluation.

Pricing checked on the vendors' official pages on 7 November 2026. Prices change; confirm before buying.

Where each one leads

Limitations

When to choose each

When neither is right

• You need joins, ad hoc analytics or multi-row ACID transactions: see SQL vs NoSQL, or distributed SQL in CockroachDB vs YugabyteDB.
• You want a flexible document model rather than query-driven tables: see Cassandra vs MongoDB.
• You are on AWS and want a fully serverless key-value service: see DynamoDB vs Cosmos DB.
• Your data is mainly time series from devices: see best time series databases.

Final recommendation

Frequently asked questions

Sources

• Apache Cassandra downloads
• Cassandra 5.0: new features
• apache/cassandra repository and licence (GitHub)
• ScyllaDB source-available licensing FAQ
• ScyllaDB Software License Agreement (GitHub)
• ScyllaDB: Apache Cassandra compatibility
• ScyllaDB 2026.3 release announcement
• ScyllaDB pricing

Checked November 2026.

How we research comparisons: our editorial method.