#tax

Progressive (marginal) tax-bracket maths as an API. You supply the bracket schedule, so it works for any country, year or tax table and never goes stale, and it is entirely currency-agnostic. The tax endpoint takes an income and a schedule of threshold:rate pairs (with an optional standard deduction) and returns the total tax, the after-tax income, the effective and marginal rates, and a per-bracket breakdown showing exactly how much is taxed in each tier. The reverse endpoint solves the inverse problem — the gross income needed to take home a target net amount on the same schedule — by bisection. The brackets endpoint validates and normalizes a schedule into labelled tiers (adding a 0% tier from zero and marking the open-ended top bracket). Everything is computed locally and deterministically, so it is instant and private. It models only the schedule you provide — fold any allowances, credits or surtaxes into the brackets or the deduction yourself — and it is not tax advice. Ideal for payroll and HR tools, salary and offer calculators, fintech and budgeting apps, and any product that shows take-home pay. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is progressive-tax maths on a schedule you supply; for gross-pay period conversion use a payroll API and for loans and interest use a finance-calculator API.

api.oanor.com/taxbracket-api

Validate and decode Indian GSTINs (the 15-character Goods & Services Tax Identification Number) instantly and entirely offline. The validate endpoint checks the structure and recomputes the official GSTIN check digit — the base-36 weighted algorithm the GSTN itself uses — and confirms the embedded state code is real, returning a clear valid/invalid verdict with the specific reasons a number fails. The decode endpoint breaks a GSTIN into its parts: the GST state/UT code and its name, the embedded 10-character PAN, the PAN holder type (company, individual/proprietor, firm/LLP, HUF, trust, government and more, read from the PAN's 4th letter), the entity registration number, the default 'Z' slot and the check digit. A states endpoint returns the full GST state-code reference for building dropdowns and lookups. Everything is pure computation — no network call, no key, no cache — so it is fast and private, ideal for checkout and onboarding forms, invoicing and e-invoice/e-way-bill pipelines, vendor master data cleansing and bulk validation. A structural GSTIN validator and decoder — distinct from EU VAT-number validation (vat), IBAN bank-account validation (iban) and card-number checks (creditcard). Note: this verifies the number's structure and check digit, not whether it is actively registered in the GSTN portal. No upstream key, no cache.

api.oanor.com/gst-api

VAT, GST and sales-tax rates for 128 countries — plus US state and Canadian province sub-rates — with a built-in tax calculator. Get the standard rate for any country (e.g. DE → 19%), compute the tax and gross total on a net amount (e.g. €100 in Germany → €19 tax, €119 total), apply a US state or Canadian province rate, or list every country. Ideal for e-commerce checkouts, invoicing, SaaS billing and pricing tools. (Standard rates, not tax advice.)

api.oanor.com/vat-api