Best Open Source Databases in 2026
The databases you can read the code of, self-host on your own servers, and never get locked out of, from relational to vector to graph.
PostgreSQL is the safest default for relational data, Redis covers in-memory caching and queues under a clean AGPLv3 license again, Supabase packages Postgres into a full self-hostable backend, and Neo4j and DuckDB cover graph and analytical workloads without a subscription. All 11 picks below ship real source code and a genuine free self-hosting path, not a trial dressed up as open source.
Every "open source database" list mixes genuinely self-hostable projects with databases that only open-source a thin client while keeping the actual server proprietary, or projects that quietly moved to a source-available license and hoped nobody would check. From the 10,000+ tools Toolradar tracks, these are the open-source databases teams actually run in production: real public source code, a license that lets you self-host without a sales call, and enough real-world adoption that help exists when something breaks.
Every pick below was checked against its current LICENSE file on GitHub, not its marketing page, because these licenses move. Redis went from a permissive BSD license to the source-available SSPL and RSAL in March 2024, then added AGPLv3 back with Redis 8 in May 2025. Elastic ran a similar loop with Elasticsearch: Apache 2.0 until 2021, then SSPL and the Elastic License, then AGPL restored as an option in September 2024. We dropped closed-source SaaS with an "open source" label bolted on (Firebase, Airtable, Notion), tools where only a thin client is open source, and anything whose free self-host tier has quietly been discontinued. What is left is ranked by production fit within its category, relational, distributed SQL, in-memory, graph, vector, analytics, and backend platforms, not by marketing spend.
Top Picks
Based on features, user feedback, and value for money.
| Tool | Starting price | Rating | Best for |
|---|---|---|---|
| PostgreSQL | Free | 4.5(1,096) | Teams that want one reliable relational database for OLTP workloads, extendable rather... |
| Redis | From $5/mo | 4.6(201) | Applications that need a fast cache, session store, or pub and sub layer in front of a... |
| Supabase | From $25/mo | 4.6(218) | Teams that want a Firebase-style developer experience without giving up the ability to... |
| DuckDB | Free | n/a | Analysts and data engineers who want fast local or in-pipeline OLAP queries without sta... |
| Neo4j | From $65/mo | 4.5(137) | Relationship-heavy data like fraud detection, recommendation engines, or knowledge grap... |
| Qdrant | Free plan | 4.5(12) | Teams adding semantic or similarity search, like RAG or recommendations, who want a ded... |
| Weaviate | From $400/mo | 4.6(29) | Search and RAG applications that need to blend exact keyword matches with vector simila... |
| Elasticsearch | Free plan | 4.3(284) | Full-text search, log analytics, and aggregations at a scale where Postgres full-text s... |
| CockroachDB | From $0.18/mo | 4.3(29) | Teams that need Postgres-style SQL with automatic multi-region resilience and cannot ac... |
| Yugabyte | Free plan | 4.5(66) | Teams that want CockroachDB-style horizontal scaling but specifically want the core dat... |
| Pocketbase | Free | 4.1(208) | Solo developers and small teams who want a Supabase-style backend without running multi... |
Teams that want one reliable relational database for OLTP workloads, extendable rather than replaced as needs grow.
Value 100/100. PostgreSQL's pricing, being entirely free and open source, is exceptionally generous and fair compared to any commercial database solution.
Watch out: Requires internal IT/DBA expertise
Applications that need a fast cache, session store, or pub and sub layer in front of a primary database.
Value 70/100. Redis Cloud pricing is straightforward at the low end, Free (30 MB) and Essentials (from $5/month) cover most development and small production workloads.
Watch out: Essentials minimum is $5/month but scales by RAM+storage, a 10 GB instance costs significantly more than the starting price suggests
Teams that want a Firebase-style developer experience without giving up the ability to self-host the underlying database.
Value 90/100. Supabase is the open-source Firebase alternative that developers actually want to use, Postgres database, authentication, storage, edge functions, and real-time subscriptions in one platform.
Watch out: Free projects pause after 7 days of inactivity: your app goes offline until someone visits it again. Not suitable for any production use, only for development and demos
Analysts and data engineers who want fast local or in-pipeline OLAP queries without standing up a data warehouse.
Value 100/100. DuckDB is entirely free and open-source, making its pricing exceptionally fair and generous compared to any commercial offering.
Watch out: No direct vendor support
Relationship-heavy data like fraud detection, recommendation engines, or knowledge graphs where SQL joins get unwieldy.
Value 60/100. Neo4j AuraDB Free is a genuine free tier, no credit card, enough to learn Cypher and prototype graph applications.
Watch out: Per-GB/month pricing makes Neo4j one of the most expensive databases at scale, 100 GB on Professional costs $6,500/month ($78,000/year) vs ~$5,000/year for equivalent RDS PostgreSQL
Teams adding semantic or similarity search, like RAG or recommendations, who want a dedicated vector engine rather than a Postgres extension.
Value 80/100. Qdrant occupies the sweet spot between developer-friendly open source and production-grade managed cloud.
Watch out: Opaque per-unit pricing: Qdrant Cloud does not publish per-vCPU, per-GB-RAM, or per-GB-storage rates on its pricing page. You must use the pricing calculator at cloud.qdrant.io/calculator or contact sales to estimate costs. This makes budget planning harder compared to competitors with transparent rate cards
Search and RAG applications that need to blend exact keyword matches with vector similarity, not just one or the other.
Value 80/100. Weaviate's pricing is fair, offering a generous free trial and a flexible entry point with the Flex plan at $45/month.
Watch out: Overage fees for exceeding Flex plan limits
Full-text search, log analytics, and aggregations at a scale where Postgres full-text search would not keep up.
Value 85/100. Elasticsearch offers a fair and generous pricing model, especially with its robust free self-hosted option.
Watch out: Increased data storage can rapidly raise costs
Teams that need Postgres-style SQL with automatic multi-region resilience and cannot accept a single point of failure.
Value 80/100. CockroachDB offers one of the most compelling free tiers in the database market, 50M Request Units and 10 GiB storage per month with scale-to-zero is enough to run a real production app at low traffic for free.
Watch out: Request Unit consumption varies dramatically by query complexity. A simple key lookup costs ~1 RU, but a full table scan or complex JOIN can consume thousands of RUs. The 50M free RUs can evaporate quickly with unoptimized queries.
Teams that want CockroachDB-style horizontal scaling but specifically want the core database under a permissive Apache license.
Value 85/100. Yugabyte's pricing is quite generous, offering a robust open-source option for those willing to self-manage.
Watch out: Managed plan costs scale with vCPU/hour usage
Solo developers and small teams who want a Supabase-style backend without running multiple containers.
Value 100/100. The pricing for Pocketbase is exceptionally generous, as it is entirely open-source and free.
Watch out: Infrastructure costs for self-hosting
Other Data & Databases worth considering
Beyond the editorial top picks, these are also strong choices we evaluated.
What Is an Open Source Database?
An open source database ships its actual server code, the part that stores and queries your data, under a license you can read, audit, modify, and self-host in production without asking permission. That is narrower than it sounds: plenty of databases call themselves "open source" while keeping the storage engine, clustering, or admin tooling behind a commercial license, or by open-sourcing only a client SDK on top of a closed managed service.
The cleanest signal is the LICENSE file in the project's repository. OSI-approved licenses like Apache 2.0, MIT, the PostgreSQL License, GPLv3, and AGPLv3 are unambiguous open source. "Source available" licenses like the Business Source License (BSL) or the Elastic License let you read and often self-host the code for free, but they add restrictions, usually a ban on reselling the software as a competing hosted service, that keep them off the OSI's approved list. Both categories show up below, labeled honestly, because "the source is public and self-hosting is free" is the bar most engineering teams actually care about day to day.
Why Open Source Matters for Databases
License changes are not hypothetical. Redis switched from its permissive BSD license to the source-available SSPL and RSAL in March 2024, which is the reason the Linux Foundation-backed Valkey fork exists; Redis then reversed course and added AGPLv3 back with Redis 8 in May 2025. Elastic ran the same round trip: Apache 2.0, then SSPL and the Elastic License in 2021, then AGPL added back in 2024. Teams that had built on the original open source promise had to fork, migrate, or accept new terms mid-project with little warning.
Running a genuinely open source database means you can audit the code that touches your data, patch it yourself if a maintainer stalls, avoid per-seat or per-node fees that scale against you as you grow, and keep a credible exit path if a vendor changes the license again. None of that requires self-hosting forever. Most of these projects also sell a managed cloud version. It means self-hosting stays an option instead of a threat a vendor can use to justify a price increase.
Key Features to Look For
OSI-approved (Apache 2.0, MIT, GPLv3, AGPLv3, the PostgreSQL License) versus source-available (BSL, Elastic License, MSCL). Read the LICENSE file, not the homepage.
Can you run it in production indefinitely for free, not just evaluate it for 30 days before a paywall appears.
SQL, Postgres wire compatibility, or a well-known language like Cypher lowers migration risk and keeps your existing drivers and ORMs working.
Some community editions strip out failover and replication, a detail that only matters once you leave a side project and need uptime guarantees.
Single-maintainer projects are fine for small apps, but check commit velocity, release cadence, and issue backlog before betting production infrastructure on one.
Extensions like pgvector and PostGIS, Prometheus exporters, and community backup tooling determine how much glue code you have to write yourself.
Mistakes to Avoid
- ×
Treating "source available" as identical to "open source." CockroachDB's Business Source License lets you read and self-host the code for free, but it is not OSI-approved and restricts reselling it as a competing service.
- ×
Pinning an old version without checking which license line it shipped under. Redis 7.4 through 7.x is SSPL and RSAL only; AGPLv3 came back with Redis 8 in 2025.
- ×
Assuming a Community Edition has everything Enterprise has. Neo4j Community drops clustering and role-based access control, details teams usually discover only after they need high availability.
- ×
Self-hosting a multi-container stack like Supabase with no backup plan, then treating an outage as someone else's problem when the infrastructure is entirely in-house now.
- ×
Reaching for a separate vector or graph database before checking whether a Postgres extension like pgvector already covers the use case inside a database the team already operates.
Expert Tips
- →
Open the actual LICENSE file in the project's GitHub repo before you build on it. Marketing pages call things "open source" loosely; the license file does not.
- →
For Redis, target 8.0 or newer specifically if AGPLv3 compliance matters to your legal team. Earlier 7.4 through 7.x builds are SSPL and RSAL only.
- →
Check Postgres extensions before adding a second database. pgvector covers a lot of "we need a vector database" requests, and PostGIS covers most geospatial ones, inside infrastructure you already run.
- →
Budget real engineering time for anything described as a "cluster" in the docs. A single Postgres or DuckDB instance is dramatically cheaper to operate than a distributed system you do not yet need.
- →
Check the free self-host ceiling before committing to a source-available database. CockroachDB's enterprise features are free only under $10 million in annual revenue; confirm your organization actually qualifies before you architect around it.
The Bottom Line
PostgreSQL is still the right default for most teams, and Supabase turns it into a full backend without taking away your ability to self-host. From the 10,000+ tools Toolradar tracks, the 11 databases above ship real, auditable source code and a genuine free self-hosting path in 2026, not a trial wrapped in open source language. Pick by category fit first (relational, distributed SQL, graph, vector), then check the actual license file before either choice costs you a migration.
Frequently Asked Questions
What is the best open source database for a new project?
For most new projects, PostgreSQL is the safest starting point: a permissive license, decades of production use, and extensions like pgvector that cover vector search without adding a second database. If you want a full backend (auth, storage, realtime) on top of it without giving up self-hosting rights, Supabase packages Postgres into that in one Apache 2.0 stack.
Is Redis still open source?
Yes. As of Redis 8 (May 2025), Redis ships under a tri-license that includes AGPLv3, an OSI-approved open source license, alongside the source-available SSPL and RSAL. That reverses the 2024 change to SSPL and RSAL only, which is why the Valkey fork exists. If your team needs a clean OSI license, target Redis 8 or newer specifically.
Is CockroachDB actually open source?
Not by the strict OSI definition. CockroachDB's core ships under the Business Source License (BSL 1.1), which is source-available: the code is public and free to self-host for individuals and companies under $10 million in annual revenue, but it is not an OSI-approved license and restricts reselling it as a competing managed service. Each version's license converts to Apache 2.0 automatically after about four years.
What is the best open source vector database?
Qdrant (Apache 2.0) and Weaviate (BSD-3-Clause) are the two leading fully open source, self-hostable vector databases, with no feature gap between the self-hosted build and the managed cloud version. If your data already lives in Postgres, the pgvector extension is often a simpler starting point than adding a dedicated vector database.
Can I self-host Supabase for free?
Yes. Supabase's full stack, Postgres, Auth, Storage, Realtime, and Edge Functions, is Apache 2.0 and available on GitHub with a Docker Compose setup for self-hosting on your own infrastructure, with no seat caps or feature gates. The hosted free tier (500 MB database) is a separate, more limited option if you would rather not manage the containers yourself.
Related Guides
Ready to Choose?
Compare features, read reviews, and find the right tool.