Finance and accounting decision
Gusto
A capable developer can build a limited payroll runner and payslip generator (useful for small single-state needs), but reproducing Gusto's full product — tax filing guarantees, licensed benefits brokerage, multi-state compliance, and enterprise-grade reliability — is expensive and operationally risky, so many teams should keep paying for the service.
Visit website↗Open-source builds that already do this
Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need — the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship.
What a replacement has to do
- Compute payroll, withhold and file taxes, send payments to employees/contractors, and produce pay stubs and compliance filings.
What it still won’t have
- licensed-broker health benefits administration and broker support
- guaranteed tax filings and backed compliance services
- access to Gusto's integrations and partner network
- dedicated support and account advisory
- scale-tested payroll infrastructure and uptime guarantees
What remains hard
- Brand trust
Join 500,000+ small and medium-sized businesses that take care of their people with Gusto.
First-year cost
Keep paying
Paying is—cheaper in year one.
On cash alone, building overtakes the subscription at 2 seats.
Money you would actually spend
Time you would spend
—
What you would spend
What we assumed
The verdict above measures whether you could build it. This one is only about money.
Runnable build prompt
Build a self-hosted payroll web app using Django (Python) + Postgres + React. Implement: employee/contractor CRUD, payroll run engine (gross-to-net with configurable deductions and tax tables for one US state), time-off and timesheet sync, ACH payment integration stub (callable service layer to plug in Plaid/Stripe Treasury later), PDF paystub and 1099/W-2 generator, admin UI to run and approve payroll, and background job processing with Celery. Out of scope: multi-state tax rules, certified tax filing, brokered benefits, and EOR. Include error handling, logging, unit tests for payroll calculations, and an integration test covering a full payroll run producing paystubs and a payment request.
How we checked
How the score was reached
- Partly verdict base52
- An open-source build was found+5
- 5 cited sources+3
- Price verified on pricing page+3
- 3/3 assessment runs agreed+4
- Evidence score67
The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time — so the same evidence always produces the same number.
How scoring works →Cited sources · 5
Every page the run actually retrieved.
- official productGusto | Online HR Services: Payroll, Benefits and everything else
- official pricingGusto Pricing, Plans & Fees (2026) | How Much Does Gusto Cost?
- official docsGusto Solo: Streamline Payroll for Your One-Employee S Corp | Gusto
- open sourcefrappe/hrms
- open sourcehorilla/horilla-hr
Integrity checks
What held up, and what did not.
