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Databases · head to head

Convex vs LanceDB

Convex logo

Convex

Databases

Reactive backend combining a document database, TypeScript server functions and live queries, source-available under the Functional Source Licence.

From
Free
Rated
-
Full reviewWebsite
LanceDB logo

LanceDB

Databases

Embedded retrieval library over the Apache 2.0 Lance columnar format, with proprietary Cloud and Enterprise tiers for serving at scale.

From
On request
Rated
-
Full reviewWebsite

The short version

  • Only Convex has a free tier, so it costs nothing to try first.
  • Each has a real cost: Convex the Functional Source Licence is not an OSI open source licence: competing use is prohibited until each release reaches its second anniversary and converts to Apache 2.0, so you may self-host but you may not build a service on it.; LanceDB the open source build is a library with no network endpoint, authentication or tenancy model, so exposing it to more than one application means writing your own service in front of it and handing every consumer credentials to the bucket.
  • They diverge on capability: Convex covers Reactive queries, LanceDB covers Embedded operation.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Convex and LanceDB actually diverge.

Attributes where Convex and LanceDB differ
AttributeConvexLanceDB
Starting priceFreeOn request
Pricing modelsubscriptionquote
Free tierYesNo

Identical on both: platforms (Web), user rating (Not yet rated), category (Databases).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Convex

  • Reactive queries
  • TypeScript server functions
  • ACID transactions
  • Document database
  • Scheduling and workflows
  • File storage
  • Text and vector search
  • End-to-end types

Only in LanceDB

  • Embedded operation
  • Lance columnar format
  • Object storage native
  • Multimodal storage
  • Vector indexes
  • Full-text and hybrid search
  • Scalar filtering
  • Dataset versioning

What people use each for

The jobs each tool is most often brought in to do.

Convex

  • Collaborative applications where several users see the same data and every client must reflect a change immediatelynot LanceDB
  • Agent backends that need durable state, scheduled work and transactional writes without assembling a queue, a database and a cachenot LanceDB
  • Small product teams who need a complete backend, including auth integration, file storage and subscriptions, without hiring infrastructure engineersnot LanceDB
  • Prototypes that must become production without a rewrite of the data layer, where end-to-end TypeScript types remove a class of integration bugsnot LanceDB

LanceDB

  • Retrieval over a dataset that includes images, audio or video, where keeping the embeddings and the source media in one format avoids a second storage systemnot Convex
  • A training and retrieval pipeline that must read the same rows for both purposes without maintaining two copies and a sync jobnot Convex
  • Prototyping search locally with the same code path that later runs against S3, with no local server to installnot Convex
  • Keeping a large, mostly cold vector corpus on object storage rather than paying to hold it in memory in a conventional vector databasenot Convex

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Convex

  • The Functional Source Licence is not an OSI open source licence: competing use is prohibited until each release reaches its second anniversary and converts to Apache 2.0, so you may self-host but you may not build a service on it.
  • Transactions are bounded at one second of user code, 16 MiB read and written, 32,000 documents scanned and 16,000 written, so every backfill, migration or bulk import has to be chunked into scheduled batches rather than written as a single operation.
  • There is no SQL and no query planner; you declare up to 32 indexes per table and traverse them, and joins are loops in TypeScript, so an unanticipated access pattern requires a schema and index change rather than a new query.
  • It is not an analytical database, so reporting means streaming data out to a warehouse and BI tools cannot be pointed at Convex directly, which adds a pipeline the architecture diagram did not originally include.
  • The application is written against Convex's function and client APIs rather than a standard protocol, so leaving means rewriting the data access layer and replacing the reactivity model, not repointing a connection string.

LanceDB

  • The open source build is a library with no network endpoint, authentication or tenancy model, so exposing it to more than one application means writing your own service in front of it and handing every consumer credentials to the bucket.
  • Queries that miss the cache pay object storage round trips, so interactive latency depends on local SSD caching or the Enterprise serving tier rather than on the library itself.
  • Concurrent writers to the same dataset coordinate through commits on the object store, so multi-writer setups can conflict and the safe pattern is a single writer per table, which is an architectural constraint on your ingest design.
  • Newly written rows are not in the index until the index is rebuilt or updated, and until then they are searched by brute force, so recall and latency drift between reindexing jobs that you have to schedule and pay for.
  • The capabilities that make it operable at scale, distributed index building, managed caching and hosted serving, live in the proprietary Cloud and Enterprise tiers, so the open licence protects the data but not the production deployment.

Pricing, plan by plan

Convex

Free
  • Free & StarterFree
    • Supports 1-6 developers
    • Reactive database
    • File storage
  • Professional$25/month per developer
    • Supports up to 20 developers
    • All Starter features
    • Log streaming
  • Business & Enterprise$2500/month minimum
    • Supports 50+ developers
    • SAML/SSO
    • Service SLAs

LanceDB

On request

No published plan breakdown. See the LanceDB review.

Which should you pick?

Choose Convex if

  • You need reactive queries.
  • You want to start without paying.
  • You also want typescript server functions.
Convex review

Choose LanceDB if

  • You need embedded operation.
  • You also want lance columnar format.
LanceDB review

Questions people ask

Is Convex or LanceDB better?
Neither clearly leads. Convex starts at Free and LanceDB at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Convex or LanceDB?
Convex has a free tier; the other does not. Paid plans start at Free for Convex and On request for LanceDB.
Does Convex or LanceDB run on more platforms?
Both run on Web, so platform support will not decide this one for you.
Can I use Convex for free?
Yes. Convex has a free tier, so you can try it without paying. LanceDB starts at On request.
What is Convex best used for?
Convex is most often used for collaborative applications where several users see the same data and every client must reflect a change immediately, agent backends that need durable state, scheduled work and transactional writes without assembling a queue, a database and a cache, small product teams who need a complete backend, including auth integration, file storage and subscriptions, without hiring infrastructure engineers, prototypes that must become production without a rewrite of the data layer, where end-to-end typescript types remove a class of integration bugs. Of those, collaborative applications where several users see the same data and every client must reflect a change immediately and agent backends that need durable state, scheduled work and transactional writes without assembling a queue, a database and a cache are not what LanceDB is typically brought in for.
What can Convex do that LanceDB cannot?
Convex covers Reactive queries, TypeScript server functions, ACID transactions, Document database. LanceDB covers Embedded operation, Lance columnar format, Object storage native, Multimodal storage.

Answered from the vendors’ own pages

Convex: Is Convex open source?

It is source-available under FSL-1.1-Apache-2.0. You may read, modify and self-host it, but competing use is prohibited until each release converts to Apache 2.0 on its second anniversary.

LanceDB: Is LanceDB open source?

The LanceDB library and the underlying Lance format are Apache 2.0. LanceDB Cloud and LanceDB Enterprise are proprietary managed products built on top of them.

Convex: Can I self-host it?

Yes. The backend, dashboard and CLI can run on your own infrastructure, with most of the features of the cloud product. Self-hosted instances include a telemetry beacon that can be disabled.

LanceDB: Do I need the managed service?

Not for development or for embedded use in a single application. You typically need it when many clients must query concurrently with predictable latency, or when index builds outgrow one machine.

Convex: Does it support SQL?

No. Data is accessed through a TypeScript query builder over declared indexes. Relationships are traversed in code, which is explicit and type-safe but means no ad hoc querying.

LanceDB: Can other tools read my data?

Yes. Lance datasets are readable from DuckDB, Polars, Pandas, PyArrow and PyTorch, which is the main practical difference from a vector database that owns its own storage.

Convex: What happens if a mutation exceeds the limits?

It fails rather than running longer, so bulk work must be split into batches and scheduled. The limits are per transaction: one second of user code, 16 MiB read and written, 32,000 documents scanned and 16,000 written.

LanceDB: How does it compare to pgvector?

pgvector keeps vectors next to relational data in a database you already run. LanceDB keeps them in object storage in a format built for random access and multimodal payloads, and scales storage independently of any server.

Convex: How does reactivity actually work?

Queries are deterministic functions and Convex records the data each one read. When a mutation changes that data, affected queries are re-run and subscribed clients receive the new result, so cache invalidation is handled by the platform.

LanceDB: What happens to updates and deletes?

Writes append new fragments and mark old rows deleted, with compaction reclaiming space later, so a workload with heavy in-place updates accumulates overhead until compaction runs.

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