Introducing Flux: Global Payroll Infrastructure and APIs

At Flux, we are rethinking what payroll infrastructure should look like for the global economy. In markets like Mexico, Brazil, and Germany, small businesses and global payroll companies still rely on spreadsheets, consultants, and manual processes to pay their teams. These markets lack the modern payroll APIs and tax automation that companies in the United States take for granted. Flux is changing that. We are building the foundational infrastructure, secure APIs for payroll calculations, tax filings, and compliance updates, so that payroll and HR software companies, banks, and accountants can launch local payroll products in weeks, not years.

The problem: payroll infrastructure stops at the border

In the United States, a developer can add payroll to a product with a few API calls. Gross-to-net math, tax tables, filing, and remittance are all available as infrastructure someone else maintains. Cross a border and that infrastructure largely disappears. Each country has its own contribution bases, its own filing calendars, its own labor rules, and its own habit of changing them at year end. So teams rebuild the same plumbing over and over, per country, usually by hand, and every manual step is a place for an error or a missed deadline to creep in.

That gap is why payroll in much of the world still runs on spreadsheets and local consultants. It is not that the rules are unknowable; it is that nobody has packaged them as reliable, real-time infrastructure a product team can build on.

What we are building

Flux is that infrastructure. Our APIs handle the parts of payroll that do not change from customer to customer but do change from country to country: calculating pay and contributions, filing and paying taxes with local authorities, and keeping every rate and rule current as regulations move. We keep the country-specific complexity current and correct underneath, and expose it through clean, predictable endpoints, so the teams building on top of us can focus on their product and their customers instead of on tax tables.

If you run a payroll or HR tech company, Flux lets you expand into new markets without building country-specific infrastructure from scratch. Our APIs automate tax calculations, file payments with local authorities, and stay on top of changing regulations. You reduce manual effort, avoid costly compliance mistakes, and deliver a better payroll experience to your customers and teams worldwide. For banks and accounting firms, the same infrastructure means you can offer a modern, local payroll product under your own brand.

Who is building it

We are assembling a team of builders, fintech engineers, and operations leaders to tackle this global problem. Our founders have scaled payroll products at Deel, Rippling, and Sphere, and we are applying that hard-won experience to close payroll's global infrastructure gap. We know where these systems break because we have built and operated them before.

If you are interested in partnering with us, we would love to talk. Join us in building the future of global payroll together.