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APIs · head to head

curl vs DuckDB

curl logo

curl

APIs

Command-line tool for transferring data using URLs with wide protocol support

From
Free
Rated
-
Full reviewWebsite
DuckDB logo

DuckDB

Databases

MIT-licensed analytical SQL database that runs inside your process, with no server, no dependencies and one writer at a time.

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: curl open-source with no vendor pricing: curl is free and open-source under GPL 3.0; no subscription or licensing costs apply; DuckDB a database file accepts one read-write process at a time; other processes must open it read-only and will not see subsequent writes, so DuckDB cannot be the shared database behind several services.
  • They diverge on capability: curl covers HTTP/HTTPS, DuckDB covers In-process execution.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which curl and DuckDB actually diverge.

Attributes where curl and DuckDB differ
AttributecurlDuckDB
PlatformsLinux, MacOS, Windows, Unix, MobileLinux, macOS, Windows, WebAssembly
CategoryAPIsDatabases
Founded19972019

Identical on both: starting price (Free), pricing model (open-source), free tier (Yes), user rating (Not yet rated).

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 curl

  • HTTP/HTTPS
  • FTP
  • Multiple protocols
  • Universal compatibility
  • Scripting tools
  • Linux support
  • MacOS support
  • Windows support

Only in DuckDB

  • In-process execution
  • Vectorised columnar engine
  • Direct file querying
  • Zero dependencies
  • Larger-than-memory queries
  • MIT licence
  • Postgres-flavoured SQL
  • Extension ecosystem

What people use each for

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

curl

  • API Developmentnot DuckDB
  • API Gatewaynot DuckDB
  • API Testingnot DuckDB
  • API Documentationnot DuckDB
  • Microservicesnot DuckDB

DuckDB

  • Transformation steps in a data pipeline that would otherwise need Spark, replaced by SQL over Parquet in a single processnot curl
  • Analytical queries embedded in an application or a dashboard where shipping a database server alongside it is not acceptablenot curl
  • Local exploration of files that are too large for a pandas dataframe but far too small to justify a warehousenot curl
  • Continuous integration and testing of analytical SQL, where a real engine can run in the test process without provisioning anythingnot curl

Where each one falls short

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

curl

  • Open-source with no vendor pricing: curl is free and open-source under GPL 3.0; no subscription or licensing costs apply
  • Commercial support costs hidden: site references 'commercial support available' but pricing is not detailed or accessible from homepage
  • No SaaS model: curl is a command-line tool and library; costs are limited to optional commercial support contracts (pricing unknown)
  • Self-support burden: free software means customers rely on community forums or undisclosed commercial support pricing

DuckDB

  • A database file accepts one read-write process at a time; other processes must open it read-only and will not see subsequent writes, so DuckDB cannot be the shared database behind several services.
  • There is no network protocol, authentication or user management, so exposing it to remote clients means writing and securing your own service around it.
  • It is built for scans and aggregations, not for many small transactions, so a workload of high-frequency single-row inserts and updates performs badly compared with SQLite or Postgres.
  • Storage files are backwards compatible but not forwards compatible, so a file written by a newer version cannot be read by an older one and every consumer of a shared file must be upgraded together.
  • Query memory settings matter: some operations still need to hold significant state, so an under-configured memory limit turns a large join or a high-cardinality aggregation into a spill-heavy query or an out-of-memory failure rather than a slow success.

Pricing, plan by plan

curl

Free
  • Open SourceFree
    • Full curl functionality
    • Community support

DuckDB

Free

No published plan breakdown. See the DuckDB review.

Which should you pick?

Choose curl if

  • You need http/https.
  • You want to start without paying.
  • You work on Linux, MacOS, Windows, Unix, Mobile.
  • You also want ftp.
curl review

Choose DuckDB if

  • You need in-process execution.
  • You want to start without paying.
  • You work on Linux, macOS, Windows, WebAssembly.
  • You also want vectorised columnar engine.
DuckDB review

Questions people ask

Is curl or DuckDB better?
Neither clearly leads. curl starts at Free and DuckDB at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, curl or DuckDB?
curl starts at Free and DuckDB at Free.
Does curl or DuckDB run on more platforms?
curl runs on Linux, MacOS, Windows, Unix, Mobile. DuckDB runs on Linux, macOS, Windows, WebAssembly.
Can I use curl for free?
Both have a free tier, so you can try either at no cost before committing.
What is curl best used for?
curl is most often used for api development, api gateway, api testing, api documentation. Of those, api development and api gateway are not what DuckDB is typically brought in for.
What can curl do that DuckDB cannot?
curl covers HTTP/HTTPS, FTP, Multiple protocols, Universal compatibility. DuckDB covers In-process execution, Vectorised columnar engine, Direct file querying, Zero dependencies.

Answered from the vendors’ own pages

curl: How much does curl cost?

curl is free and open-source software under the GPL 3.0 license. There is no cost to download, use, or modify the software.

Source
DuckDB: Can multiple applications share one DuckDB database?

Not for writing. One process holds the database read-write; others may attach read-only and will not see later writes. Shared multi-writer access needs a different database or a table format with a catalogue.

curl: Is commercial support available for curl?

Yes. The curl website references 'commercial support available,' but pricing and details are not disclosed on the homepage and require visiting the support page.

Source
DuckDB: Is it a replacement for a data warehouse?

For single-node analytical workloads up to a few hundred gigabytes it very often is. It is not a replacement when many concurrent users need a shared, governed, always-on service.

curl: Can I sponsor curl financially?

Yes. The curl website offers an option to 'Sponsor curl financially.' Visitors can donate to support curl development, but the donation link must be accessed through the site's support section.

Source
DuckDB: Do I have to load data into it?

No. It queries Parquet, CSV, JSON and Arrow in place, including on object storage. Its own storage format is optional and mainly useful when you want indexes, constraints and faster repeated access.

DuckDB: What is MotherDuck's relationship to it?

MotherDuck is a separate company offering a managed and hybrid service built on the DuckDB engine. DuckDB itself remains MIT-licensed and independent of it, with the IP held by the DuckDB Foundation.

DuckDB: Is it suitable for OLTP?

No. It is designed for analytical scans. For transactional workloads with frequent small writes, SQLite or Postgres is the right tool.

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