OpenSalesTax
OpenSalesTax is a free, self-hosted API that calculates sales tax on US transactions using public data and per-state modules.
What OpenSalesTax is
OpenSalesTax is a free, self-hosted API that calculates sales tax on US transactions using public data and per-state modules. The project says its modules cover 52 jurisdictions; each published data dump includes all 48 jurisdictions that impose sales tax. It can calculate tax for line items and provide breakdowns by state, county, city, or district. Documented item categories include general goods, clothing, groceries, prescription drugs, prepared food, and digital goods. Its data comes from Streamlined Sales Tax files and state Department of Revenue publications, not paid tax feeds. The engine can be installed from source or run with Docker, using PostgreSQL by default and optional MariaDB support. Access defaults to open access with per-IP rate limits; API-key mode uses an X-API-Key header and supports per-key limits and usage tracking. Data dumps reflect the quarterly SST file current at release, and newer source data can be loaded. The project notes incomplete sub-state tax stacking for Colorado home-rule cities and Louisiana parish-level collectors. It is pre-1.0, and its calculations are not legal or tax advice.
Good
- Free plan: free.
- Calculates line-item tax with jurisdiction breakdowns.
- Supports API-key limits and usage tracking.
- PostgreSQL is supported by default.
Watch out
- Pre-1.0 project.
- Incomplete sub-state stacking in some Colorado and Louisiana areas.
- Docker restore requires adding psql or using source installation.
- Calculations are not legal or tax advice.
Who it suits
OpenSalesTax suits developers or organizations building US transaction tax calculations who can self-host an API. Users should be prepared to verify calculations with the relevant state Department of Revenue before remitting.
Verdict
OpenSalesTax provides a self-hostable way to calculate and inspect US sales tax from public data. Its stated jurisdiction gaps and pre-1.0 status merit review before relying on the results.
Plans and prices
From OpenSalesTax's own pricing page, checked 4 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Free / open source | Free | Apache 2.0 · self-hostable · US sales tax calculation API |
| Free self-hosted engine | Free | Docker or source deployment · REST API · hosting and maintenance are your responsibility |
The facts
Each one read from OpenSalesTax's own pages, with the date it was checked.
What it does
- Adoption status
- The public users registry says there are no listed self-hosters or integrators yet and that OpenSalesTax is pre-1.0.checked 4 Oct 2026
- Advice disclaimer
- The project describes its output as calculation only, not legal or tax advice, and tells users to verify results with their state revenue department.checked 15 Oct 2026
- API access
- Authentication defaults to open access with per-IP rate limiting, while an API-key mode requires an X-API-Key header and supports per-key rate limits and usage tracking.checked 4 Oct 2026
- API endpoints
- The documented API exposes health, jurisdiction coverage, ZIP-based rates, and POST tax calculations under version 1 routes.checked 15 Oct 2026
- Calculations
- The API calculates tax for line items and can return a breakdown by state, county, city, or district jurisdiction.checked 4 Oct 2026
- Contributions
- Contributors must sign commits using the Developer Certificate of Origin process.checked 15 Oct 2026
- Coverage
- The project says it has modules for 52 jurisdictions, with all 48 sales-taxing jurisdictions loaded into each published data dump.checked 4 Oct 2026
- Coverage limitation
- Colorado home-rule cities and Louisiana parish-level collectors are not fully represented, so sub-state stacking is incomplete there.checked 15 Oct 2026
- Database support
- MariaDB is available through an optional installation extra, but the bundled release dump is PostgreSQL COPY format.checked 15 Oct 2026
- Data refresh
- Operators can bypass the bundled dump and fetch and load newer state data directly from upstream sources.checked 15 Oct 2026
- Data-release limitation
- Release dumps before v0.59.0 omitted 23 taxing states and require restoration from a corrected asset.checked 15 Oct 2026
- Data sources
- The project uses Streamlined Sales Tax files and state Department of Revenue publications, and says it does not ingest paid tax data feeds.checked 4 Oct 2026
- Deployment
- Users can install from source with Poetry and PostgreSQL or run the stack with Docker Compose.checked 15 Oct 2026
- Docker limitation
- The published runtime image lacks the psql client, so the documented data-restore command fails in the container until that package is added.checked 15 Oct 2026
- Holiday rules
- The engine includes holiday-aware calculations, illustrated by a Texas clothing exemption example.checked 15 Oct 2026
- Hosting
- The engine can be installed from source or run with Docker and requires PostgreSQL by default; MariaDB support is available as an optional extra.checked 4 Oct 2026
- Independent limitation
- WiserReview says users must host and update the engine, handle remittance themselves, and that marketplace and multi-vendor allocation are not covered.checked 15 Oct 2026
- Independent pricing assessment
- WiserReview lists the engine and WooCommerce plugin at $0 software cost, with hosting and maintenance left to the user.checked 15 Oct 2026
- Item categories
- Documented categories include general, clothing, groceries, prescription drugs, prepared food, and digital goods.checked 4 Oct 2026
- Jurisdiction detail
- Calculation responses break tax into state, county, city, and district jurisdictions so totals can be reconciled.checked 15 Oct 2026
- License
- The engine is released under the Apache License 2.0.checked 15 Oct 2026
- Limitations
- The project identifies incomplete sub-state tax stacking for Colorado home-rule cities and Louisiana parish-level collectors.checked 4 Oct 2026
- Magento integration
- The Magento 2 module supports U.S.-destination, USD checkouts and can fail back to Magento tax tables when the engine is unavailable.checked 15 Oct 2026
The company
- Maker identity
- The repository identifies Eric Osterberg as the initial project maintainer responsible for direction and license decisions.checked 15 Oct 2026
