For most new applications, start with PostgreSQL. It combines relational integrity, transactions, complex SQL and extensibility without forcing an unusual deployment model. Choose SQLite for an embedded or local-first product, MySQL or MariaDB when your team already operates that ecosystem, and a specialized system only when your data shape or scale clearly requires it.
The comparison below separates data model, consistency, scaling, operations and licensing so you can make a defensible choice rather than picking by popularity alone.
How to choose a database
Write down the answers to these questions before comparing products:
- What is the data shape? Relational rows, JSON documents, key-value pairs, graph relationships, wide columns or time-series measurements each favor different engines.
- What must be consistent? Financial balances and inventory usually need transactions and integrity constraints. Caches and telemetry may accept different trade-offs.
- Where will it run? A single process, one server, a mobile device and a multi-region cluster have very different operational requirements.
- How will it scale? Some systems scale up on one node; others partition data across nodes. Horizontal scale usually requires deliberate key design and topology planning.
- Who will operate it? Assess backup, recovery, upgrades, monitoring, drivers and managed-service availability alongside query performance.
- What license is acceptable? “Open source” is not one license. Check the current server, client and hosted-service terms for the exact release you deploy.
Quick comparison of the 13 systems
| System | Model and query style | Best fit | Scaling and operations | License note |
|---|---|---|---|---|
| PostgreSQL | Object-relational SQL; transactions, constraints and extensions | General-purpose applications and complex workloads | Primarily scale-up with replication and ecosystem tools; validate a managed option | PostgreSQL license; verify the release terms |
| MySQL | Relational SQL | Web stacks with existing MySQL expertise or framework defaults | Established replication and hosting ecosystem; confirm edition capabilities | Check the current Community/other edition and license before deployment |
| MariaDB | Relational SQL; MySQL-family compatibility | Teams wanting a GPL-licensed MySQL-family server | Documentation covers deployment, security, high availability and performance | GPL-licensed; verify components and version terms |
| SQLite | Embedded relational SQL in a single file | Mobile, desktop, local-first and device software | No database server to operate; move to client/server for centralized concurrent writes | Public-domain-style terms; check the exact distribution |
| MongoDB | Document database with JSON-like records | Flexible documents whose shape evolves quickly | Distributed deployment is available; model indexes and consistency deliberately | Confirm the current server and hosted-service license; “open source” status can depend on the edition |
| Redis | In-memory key-value data store | Caching, queues and low-latency counters | Designed for speed; normally pair it with a durable system of record | Check the current Redis license and compatible forks |
| Apache Cassandra | Distributed wide-column NoSQL | Large, highly available workloads with known access patterns | Partitions across nodes; consistency and topology must be designed up front | Apache license family; verify the current release |
| Apache CouchDB | Web-oriented JSON documents | Document-centric applications and HTTP-oriented workflows | Distributed replication model; test conflict and recovery procedures | Apache license family; verify current terms |
| Neo4j | Native graph database; Cypher | Relationship traversal as the primary workload | Standalone and clustered deployments; administer nodes and cluster topology | Check the current edition and license for production use |
| Firebird | Relational SQL | Compact server or embedded deployments | Small operational footprint; validate drivers and support for your platform | Verify current release, driver and license details |
| TiDB | Distributed SQL with MySQL-compatible ecosystem | Horizontal scale while retaining a SQL workflow | Multi-node architecture; test compatibility and consistency behavior | Verify current compatibility and licensing |
| CockroachDB | Distributed SQL | Resilient multi-node applications | Designed for distributed operation; plan latency, consistency and failure recovery | Licensing has changed over time; check the edition and current license |
| InfluxDB | Time-series measurements and events | Metrics, sensors and timestamped streams | Choose retention and query architecture for your workload | Multiple editions and changing boundaries require a current license check |
Relational databases for general application data
PostgreSQL: the strongest default
PostgreSQL is an open-source object-relational database that uses and extends SQL. Its ACID-compliant transaction model, integrity features and extensibility suit applications with interconnected data, reporting and evolving requirements. Choose it when foreign keys, sophisticated joins, reliable transactions or custom extensions matter. It can run on major operating systems, and its broad driver ecosystem reduces application lock-in.
#1 Best Overall
MySQL: choose the ecosystem you already have
MySQL remains a practical general-purpose relational choice when a framework, hosting provider or operations team is already built around it. Existing schemas, runbooks and driver support can outweigh theoretical differences. Check the current edition, feature set and license because MySQL’s product and licensing distinctions matter to redistribution and hosted use.
MariaDB: a MySQL-family alternative
MariaDB is a GPL-licensed, multithreaded relational DBMS with MySQL-family heritage. It is reasonable when your team wants familiar SQL and tooling but prefers MariaDB’s project and licensing model. Read the version-specific compatibility notes before assuming that every MySQL feature, driver or extension behaves identically.
SQLite: an application component, not a shared server
SQLite stores a relational database in a single file and runs inside your application. That makes it excellent for mobile, desktop, local-first and device software, test fixtures and small utilities. It eliminates a database server, network hop and separate backup service. Use a client/server engine when many users must write to one centralized database, when operational access controls are central, or when the file-based model becomes a bottleneck.
Firebird: compact relational deployments
Firebird is worth evaluating for a compact server or embedded relational deployment, especially when its drivers match your language and platform. Confirm the current release, support horizon, embedded behavior and license before committing; those details determine whether it is a sustainable choice for a new project.
Document and key-value databases
MongoDB: flexible JSON-like records
MongoDB models records as documents rather than rows. It fits applications in which related data is naturally read together and fields evolve without a rigid relational schema. You still need explicit index, validation, transaction and consistency decisions. Confirm the current server license and hosted-service terms before describing a deployment as open source in the strict Open Source Initiative sense.
Apache CouchDB: documents over the web
Apache CouchDB is a web-oriented JSON document database. Its HTTP-centric approach can simplify integrations where documents are exchanged directly with clients or services. Evaluate replication, conflict handling, indexing and recovery with realistic data; document flexibility does not remove the need for deliberate access patterns.
Redis: speed beside the system of record
Redis is a high-speed, commonly in-memory key-value store used for caching, real-time analytics, queues and counters. It is usually a supporting component rather than the only durable database for business records. Define eviction, persistence, expiration and restart behavior, and check the current Redis license or a compatible fork before deployment.
Distributed and specialized systems
Apache Cassandra: predictable, partitioned workloads
Cassandra is a distributed wide-column database for large-scale, highly available workloads. It works best when you can state the read and write patterns in advance and design partitions around them. It is not a drop-in relational replacement: denormalize intentionally, choose consistency levels and validate topology and repair procedures with the current project documentation.
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Neo4j is a native graph database administered with Cypher. Choose it when traversing multi-hop relationships—recommendations, dependency maps, fraud networks or knowledge graphs—is central to the application. Standalone and clustered deployments are documented, but graph modeling, memory sizing and cluster operations require specialized skills.
TiDB: distributed SQL with MySQL compatibility
TiDB targets teams that want horizontal scaling and distributed resilience while retaining a MySQL-compatible SQL ecosystem. Test the exact compatibility surface used by your framework, including SQL modes, drivers, transaction behavior and operational tooling. Verify the current license before production adoption.
CockroachDB: resilient multi-node SQL
CockroachDB is designed for multi-node applications that must continue operating through node or zone failures. Its distributed consistency and latency behavior require workload testing, especially for cross-region writes. Licensing has changed over time, so select an edition only after reading its current terms.
InfluxDB: measurements and event streams
InfluxDB is specialized for time-series measurements, metrics and sensor-style events. Its value comes from timestamp-aware ingestion, retention and querying rather than general relational joins. Decide how long raw and downsampled data must remain available, then confirm which current edition and open-source components provide those capabilities.
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Decision recipes
- New SaaS or business application: PostgreSQL unless a strong existing MySQL/MariaDB standard dictates otherwise.
- Mobile, desktop or offline-first app: SQLite first; introduce a client/server database when centralized multi-user writes dominate.
- Flexible documents: MongoDB or CouchDB when document evolution and aggregate reads matter more than joins.
- Cache or ephemeral real-time state: Redis alongside a durable system of record.
- Known access patterns at very large scale: Cassandra, with partition and consistency design completed before coding.
- Relationship-heavy queries: Neo4j.
- Distributed SQL requirement: TiDB or CockroachDB after compatibility, consistency, latency and license testing.
- Metrics and sensor data: InfluxDB after choosing retention and edition boundaries.
Migration, backup and licensing checks
- Model the highest-risk query and transaction before selecting an engine.
- Build a small workload test using production-shaped rows, documents or events; measure latency under concurrent reads and writes rather than a single query.
- Exercise backup restoration, point-in-time recovery where available, schema or index changes, and a node or process failure.
- Inventory drivers, migration tools, observability integrations and the skills your team can staff.
- Read the current server, client, extension and hosted-service licenses. A project may combine GPL, Apache, PostgreSQL, BSD or public-domain-style components, and a hosted offering may have separate terms.
- Record the chosen version and edition in your architecture decision so a future license or compatibility change is visible during upgrades.
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Frequently Asked Questions
Can I use more than one database in the same project?
Yes. A common design keeps authoritative relational data in PostgreSQL, uses Redis for cache or short-lived state, and sends metrics to a time-series system. Define ownership, consistency and recovery for each store before splitting data.
Is a document database automatically schema-free?
No. MongoDB and CouchDB allow flexible document shapes, but production systems still benefit from validation rules, versioned migrations, indexes and documented invariants.
When should a startup adopt a distributed database?
Adopt one when measured availability, geographic or throughput requirements justify its operational complexity. Start with the simplest engine that satisfies current constraints and test a distributed design before a migration becomes urgent.
Does an open-source license guarantee a free managed service?
No. A project license covers particular software components; hosted providers can impose separate pricing, feature and service terms. Review both before choosing a managed deployment.
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