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APIs: 187 open source projects.

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187 projects146 maintained139 on the map37 jurisdictions + globalFacts checked 6 Oct 2026

Browse these by tax area

Income tax Corporate tax Benefits Payroll tax VAT & indirect Cross-cutting

aade-mydataPHP client for Greece's AADE myDATA invoicing API: send, cancel and retrieve invoices.APIGR

Attest.NET library that validates ID numbers, tax codes, VAT numbers and postal codes in 87 countries.APIGlobal

BelgiumVatChecker.NET Web API that validates Belgian and EU VAT numbers using the VIES service.APIBE · EU

BrevJVM library to write and read Peppol BIS Billing 3.0 invoices and credit notes, with Norwegian identifiers.APINO · EU

cbam-apiGo API on the EU Carbon Border Adjustment Mechanism (CBAM) data model.APIEU

chinaport-data-signatureSigns China E-Port customs messages (CEB, 179 data) for cross-border e-commerce declarations.APICN

commerceguys/taxPHP tax library for commerce applications: tax types, zones and rates.APIGlobal

Corporation-Accounting-SkillFastAPI service for an accountant agent: ASC 740 provision checklists, book-to-tax differences, journals.APIUSLicence unknown

ct600-filingCommand-line tool that files a CT600 corporation tax return with HMRC.APIUK

customs-api (Maldives)PHP SDK for the Maldives Customs Service API: trader lookup.APIMV

customs-domainPHP domain logic for commodity code validation, UK Trade Tariff mapping and compliance rules.APIUK

DomibusDomibus, the European Commission's open AS4 message handler for eDelivery, used for e-invoicing exchanges.APIEU

Dutch Peppol Authority validationSchematron and XSL validation artefacts for SI-UBL and NLCIUS e-invoices from the Dutch Peppol Authority.APINL

e-factura-goGo client for Romania's ANAF e-Factura and e-Transport APIs, with a UBL builder and a CLI.APIRO

einvoice_atSelf-hosted Austrian platform to create, validate and convert ebInterface and Peppol BIS Billing invoices.APIAT

einvoicing (JavaScript)JavaScript library to create and parse EN 16931 e-invoices and popular extensions.APIEU

eInvoicing-EN16931Validation artefacts for EN 16931, the European e-invoicing standard.APIEU

eric-rsRust bindings and SDK for ERiC, the ELSTER library for submitting German tax filings.APIDE

ESJ (EN 16931 Semantic JSON)JSON binding of the EN 16931 invoice model, with a Java library, CLI, validation and UBL/CII conversion.APIEU · DE

eu-vat-evidence.NET library for EU VAT number validation and compliance evidence, in two NuGet packages.APIEU

factur-xPython library for Factur-X, the e-invoicing standard for France and Germany.APIEU · FR · DE

Facturae-PHPPHP library to create, sign and send Spanish Facturae e-invoices without other dependencies.APIES

fatoorityRust toolkit for Saudi ZATCA Phase 1 and Phase 2 e-invoicing.APISA

fattura-elettronicaPHP library that generates Italian e-invoices in the XML format of the Agenzia delle Entrate.APIIT

FatturaElettronica.NETItalian electronic invoicing for businesses and public administration, in .NET.APIIT

faturaPHP library for Türkiye's GİB e-Arşiv portal: e-invoices, e-SMM and e-Müstahsil receipts.APITR

FiscalBr.NETC# library that generates Brazil's SPED files and other tax and accounting declarations.APIBR

go-financeGo library with exchange rates, VAT number validation and IBAN/BIC conversion.APIEU

GOBLGo library and schemas for electronic business documents, especially invoices.APIGlobal · EU

gobl.es.facturaeConverts GOBL documents into Spain's FacturaE e-invoice format.APIES

gobl.es.verifactuConverts GOBL documents into VeriFactu records and sends them to Spain's tax agency.APIES

HMRC Advance Tariff Rulings serviceHMRC's Advance Tariff Rulings service: application frontend, case backend, rulings search, case manager.APIUK

HMRC Assist (Self Assessment)API that generates an HMRC Assist report of risk messages for a Self Assessment return before submission.APIUK

HMRC CDS FinancialsHMRC's CDS financial services: duty deferment statements, cash and guarantee accounts.APIUK

HMRC Country-by-country reportingHMRC's service for uploading country-by-country reports as XML files, with its backend and file validation.APIUK

HMRC CRS/FATCA reporting serviceHMRC's CRS and FATCA reporting service: registration, institution management and report upload.APIUK

HMRC Customs Declaration Service APIsHMRC's Customs Declaration Service APIs: submit, amend and cancel declarations, upload documents.APIUK

HMRC Customs Exports Declaration ServiceHMRC's Customs Exports Declaration Service: trader frontend, declaration backend and the movements service.APIUK

HMRC customs inventory linking APIsHMRC's inventory linking APIs for import declarations and for export consignment consolidation and movement.APIUK

HMRC Digital Platform Reporting serviceHMRC's Digital Platform Reporting service (DAC7 rules): registration, operators, seller-data XML filing.APIUK

HMRC Digital Services TaxHMRC's Digital Services Tax service: registration and returns, with a frontend and test stubs.APIUK

HMRC Enhanced Self Serve Time To PayHMRC's payment-plan journey for tax debts: eligibility check, affordability and plan selection, and backend.APIUK

HMRC EORI servicesHMRC's EORI services: an API that checks a GB EORI number and returns trader details, with its backend.APIUK

HMRC EU VAT refundsHMRC service for EU VAT refund claims, started in 2026.APIUK

HMRC financial transactions (VAT)Service returning MTD VAT liabilities, payments and late-payment penalty details, with direct debit checks.APIUK

HMRC Import Control System (ICS2)HMRC's import control services: entry summary declaration store, ICS2 WSDL schemas, safety and security guide.APIUK

HMRC Income Tax (MTD) servicesHMRC service that collects dividend, interest, Gift Aid, CIS, employment and pension data for Income Tax MTD.APIUK

HMRC individuals charges APIAPI to view and manage individuals' pension and high income child benefit charges.APIUK

HMRC Mandatory Disclosure Rules serviceHMRC's mandatory disclosure rules (MDR) service: credentials and subscription details, XML checks, submission.APIUK

HMRC New Computerised Transit System (NCTS)HMRC's transit services: traders API, NCTS validator and converter, movement store, documents, guarantees.APIUK

HMRC payments servicesHMRC's payment services: processor, orchestrator, card, mobile and telephone payments, national direct debit.APIUK

HMRC penalties serviceHMRC's late-submission and late-payment penalty service: backend, VAT and income tax frontends, appeals.APIUK

HMRC Pillar 2 servicesHMRC's Pillar Two service code: the submission API, the registration frontend and backend, and test stubs.APIUK

HMRC Self Assessment accounts APIAPI for a Self Assessment account: balance (overdue, payable, pending), charges, payments and allocations.APIUK

HMRC Self Assessment calculation APIsHMRC's MTD APIs that trigger and return a Self Assessment calculation, with the liability, BSAS and BISS APIs.APIUK

HMRC Self Assessment refundFrontend for claiming a Self Assessment refund.APIUK

HMRC Senior Accounting Officer serviceHMRC's Senior Accounting Officer service: registration, hub, notification and certificate submission.APIUK

HMRC submission trackerService that tracks the status of forms and submissions sent to HMRC.APIUK

HMRC third-party payments APIExternal API that lets third-party software initiate a payment to HMRC.APIUK

HMRC Time to PayHMRC's Time to Pay services: the arrangement backend, the self-service frontend, proxy API and taxpayer data.APIUK

HMRC VAT APIHMRC's Making Tax Digital VAT API: obligations, returns, payments, liabilities and penalties.APIUK

HMRC VAT repayment trackerService where businesses track the progress of a VAT repayment: frontend and backend.APIUK

HMRC View and change income tax (MTD)Frontend where MTD income tax customers view calculations, charges and payments and make changes.APIUK

hmrclibTyped Python clients for 73 HMRC APIs: Pillar 2 submission, customs declarations, Making Tax Digital and more.APIUK

hs-code-lookupJavaScript library that parses, validates and looks up HS codes with MFN duty rates for US, EU, UK and China.APIUS · EU · UK · CN

HSN-Code-PackageZero-dependency HSN and SAC code lookup and India GST toolkit, on npm as hsn-code-package.APIIN

hstc-apiFree REST API for searching the Vietnamese HS code explanatory notes.APIVN

ibericode/vatPHP library for European VAT: rates, VAT number validation and country checks.APIEU

invkitTypeScript library for invoice totals with several tax types, stacked discounts and extras.APIGlobal

invoicesuitePHP library to create, read and validate XRechnung, ZUGFeRD and Factur-X e-invoices.APIDE · EU

kaltblutJava library for handling ZUGFeRD e-invoices.APIEU · DE

KoSIT validatorGermany's official validator engine for XML e-invoices: checks XSD and Schematron, then reports.APIDE · EU

KSeF official clients (C#, Java)Official C# and Java clients for KSeF, Poland's national e-invoice system, from the Ministry of Finance.APIPL

ksef-apiIntegration guide for KSeF 2.0, Poland's national e-invoicing system.APIPL

ksef-php-clientPHP client for KSeF, Poland's national e-invoicing API.APIPL

ksef4jJava client for Poland's KSeF 2.0 e-invoice API, with fluent builders and Spring Boot autoconfiguration.APIPL

ksefujValidator for Polish KSeF FA(3) e-invoices: XSD, business rules and tax maths, as web app, npm and CLI.APIPL

LaravelVerifactuLaravel package that records invoices under Spain's VeriFactu system.APIES

Mews.Fiscalizations.NET libraries that report e-invoices and receipts to six countries' fiscalisation systems, by a hotel vendor.APIAT · DE · ES · HU · IT · SE

mustangprojectJava library, validator and tool for e-invoices: Factur-X/ZUGFeRD, XRechnung and UN/CEFACT CII.APIEU · DE

mydataPython client and CLI for Greece's myDATA tax platform, with data models and an invoice workflow helper.APIGR

myinvoisUnofficial TypeScript SDK for Malaysia's MyInvois e-invoicing API, with UBL 2.1 and digital signing.APIMY

NAV DCC-APISchemas and Java models of the Hungarian tax authority's DAC9 (GloBE return), DAC8 and CARF exchange API.APIHU · EU

NAV eRECEIPTPublic repository of Hungary's e-receipt (eNyugta) cash-register system: developer docs, XSDs and examples.APIHULicence unknown

NAV eVATPublic repository of Hungary's eVAT system: M2M interface docs, schemas and example XML for the VAT return.APIHULicence unknown

NAV M2MSchemas, example XML and Swagger specifications for machine-to-machine form submission to Hungary's NAV.APIHU

NAV Online InvoicePublic repository of Hungary's Online Invoice real-time reporting system: schemas, docs and examples.APIHU

nfe (Java)Java library for Brazil's electronic invoice (Nota Fiscal Eletrônica).APIBR

NFeWizardNode.js library for the SEFAZ web services behind Brazil's electronic invoice (NF-e).APIBR

node-sales-taxNode.js sales tax and VAT calculator with offline rates and an optional VAT number check.APIGlobal

open-logistics-toolsHS code validation and Bangladesh customs duty calculation utilities, published on npm.APIBD · Global

OpenXRechnungToolboxDesktop toolbox to view and validate XRechnung and other EN 16931 e-invoices.APIDE

org.coderic.ws.sunatJava JAXB bindings of UBL schemas for integrating with Peru's SUNAT electronic invoice web services.APIPE

Oxalis-NGOxalis Next Generation, open-source implementation of the OpenPeppol AS4 profile for access points.APIEU · NO

Peppol BIS Billing 3.0Specification and validation rules for Peppol BIS Billing 3.0 e-invoices, from OpenPeppol.APIEULicence unknown

peppol-billingTypeScript library that generates and parses Peppol BIS Billing 3.0 (UBL 2.1) invoices and credit notes.APIBE · EU

peppol-bis-billing-3-generatorJava code that generates Peppol BIS Billing 3 invoice XML.APINO · EU

peppol-toolkitTypeScript toolkit to generate and read Peppol UBL e-invoices.APIEU

phase4AS4 client and server library with built-in Peppol and CEF eDelivery support.APIEU · Global

phive-rulesE-invoice validation rules for the phive engine, covering many countries.APIGlobalLicence unknown

phoss APphoss AP, an open-source Peppol Access Point server by the author of phase4 and phive.APIEU

phoss SMPphoss SMP, a Peppol and OASIS BDXR service metadata publisher server.APIEU

php-zatca-xmlPHP library for ZATCA Fatoora e-invoices: certificates, XML, signing, QR codes and API submission.APISA

PolicyEngine APIREST API that computes the impact of tax and benefit policies with the PolicyEngine models.APIGlobal

PyNFePython library for the web services of Brazil's electronic invoice (NF-e).APIBR

python-stdnumParse and validate VAT, TIN and company numbers for dozens of countries.APIGlobal

QWED-TaxDeterministic check, built on the Z3 solver, that verifies AI-generated tax decisions before they run.APIUS · IN

SAF-T AOXML schema and validation notes for Angola's SAF-T (AO) file, kept by Portugal's software association.APIAO

Saft-PT for PHPPHP framework for Portugal's SAF-T audit files; e-invoice submission is in a separate enterprise edition.APIPT

siiLibrary for SII, the Spanish tax agency's immediate VAT reporting system.APIES

Skatteetaten mva-meldingenImplementation guide and validation material for the Norwegian VAT return (mva-melding) API.APINO

Skatteetaten SAF-TNorwegian SAF-T schemas, code lists and test files published by the Tax Administration.APINOLicence unknown

Skatteetaten skattemeldingenCode and specs for filing the Norwegian tax return: APIs, a validation service, XSDs and a Kotlin calculation.APINO

Skatteetaten suppleringsskattThe Norwegian Tax Administration's notes on GloBE Information Return filing: XML format, XSD check, test file.APINOLicence unknown

Skattestyrelsen RSU B2B sample clientsDanish Tax Agency sample Java and .NET clients that submit VAT returns and fetch periods and receipts.APIDKLicence unknown

StampbenchTypeScript library and CLI to validate, repair and generate XRechnung and EN 16931 e-invoices.APIDE · EU

tax-idsRust crate that validates VAT and GST numbers in the EU, UK, Switzerland and Norway.APIEU · UK · CH · NO

tax-kalculatorKotlin Multiplatform library that works out UK take-home pay after tax, National Insurance, pension and loans.APIUK

Taxsim.jlJulia interface to TAXSIM, the NBER's calculator for US federal and state income taxes.APIUS

ubl-invoicePHP library to read and create UBL electronic invoices.APIGlobal

ubl-peppolPHP library that builds UBL 2.1 e-invoices for Peppol BIS Billing 3.0.APIEU · NL · BE

UK Online Trade TariffThe UK Online Trade Tariff: API, website, admin tool and electronic tariff file for codes, duties and quotas.APIUK

ura-efris-php-sdkPHP SDK for the Uganda Revenue Authority's EFRIS e-receipting and e-invoicing API.APIUG

valvatRuby gem that validates EU and UK VAT numbers, standalone or as an ActiveModel validator.APIEU · UK

vat (adaptive)Cloudflare Worker that validates EU VAT numbers via the VIES SOAP service and returns JSON.APIEU

vat-calculatorPHP library that applies EU VAT rates and MOSS rules and validates VAT numbers.APIEU

VATcomplyRust API server for VAT number validation, ECB exchange rates, VAT rates and IP geolocation.APIEU

VATValidationVAT number validator with GUI, CLI and REST API for German, EU, UK and Swiss checks.APIDE · EU · UK · CH

VeriFactuSends invoicing records to Spain's tax agency (AEAT) under the VeriFactu rules.APIES

Verifactu-PHPPHP library for VERI*FACTU, the Spanish tax agency's invoice reporting system.APIES

vies-checkerTypeScript validator for EU VAT numbers using the European Commission's VIES service.APIEU

vies-client (LGx0)Zero-dependency Java client for validating EU VAT numbers through the VIES REST API.APIEU

vies-dotnet.NET library that validates EU VAT numbers through the European Commission's VIES service.APIEU

WencheFiles annual accounts, the shareholder register return and the tax return for Norwegian limited companies.APINO

XRechnung validator configurationThe official XRechnung and EN 16931 validation scenarios for the KoSIT validator.APIDE · EU

XRechnung-for-DelphiXRechnung, ZUGFeRD and Peppol BIS Billing library for Delphi and FreePascal.APIDE

ZATCA (Salla)PHP package for Saudi ZATCA e-invoicing, phases 1 and 2: CSR, invoice signing and QR codes.APISA

zatca-kitTypeScript toolkit for Saudi ZATCA e-invoicing: CSR, QR codes, XAdES signing and API calls.APISA

zimra-fdmsTypeScript SDK for ZIMRA's fiscalisation system: device registration, mTLS, receipt signing, offline queue.APIZW

AvaTax REST v2 PHP SDKPHP SDK for the AvaTax REST v2 API, a hosted tax calculation service.APIUSNeeds a paid service

cakephp-vat-number-checkCakePHP plugin that normalises a VAT number and checks whether it is valid.APIEUInactive since 2019

checkvatScala library that checks whether an EU VAT number is valid, following the VIES specification.APIEUArchivedLicence unknown

CountryValidator.NET library that validates VAT codes and national and tax ID numbers for 82 countries.APIGlobalInactive since 2024

DGFiP FARITASFARITAS, DGFiP's tourist-tax collection service for booking platforms, local authorities and accountants.APIFRInactive since 2024

e_invoice_qrcode_readerFlutter app that decodes and shows the QR code on Saudi ZATCA e-invoices.APISAArchivedLicence unknown

e-invoice-tsTypeScript SDK for the e-invoice.be Peppol API: create and manage e-invoice documents from server code.APIEUNeeds a paid service

e-invoice-validator (easybill)Validation service for UBL and CII e-invoices against EN 16931, XRechnung, Peppol BIS and Factur-X rules.APIEU · DEInactive since 2025

efaturaCreates invoices through Türkiye's e-Arşiv system.APITRInactive since 2025

egypt-eta-tax-apiLaravel helper that hashes and submits e-receipts to the Egyptian Tax Authority's pre-production API.APIEGInactive since 2025

einvoicing (PHP)PHP library to read and create EN 16931 European e-invoices as UBL; CII is on the roadmap.APIEUInactive since 2025

eori (PHP)PHP EORI number validator.APIEUInactive since 2024

estonian_e_invoicePython package that generates e-invoices in Estonian e-invoice standards.APIEEInactive since 2020

Factur-X LibreOffice extensionLibreOffice Calc extension that generates Factur-X PDF invoices.APIEU · FR · DEArchived

HMRC DAC6 disclosure serviceHMRC's DAC6 cross-border arrangement disclosure service, archived in March 2024 when the UK moved to MDR.APIUKArchived

hscode (Go)Go package embedding the HS nomenclature with validation, lookup and search; data under PDDL.APIGlobalInactive since 2025

hyperway.NET Core Peppol Access Point implementation, last changed in 2018.APIEUInactive since 2018Licence unknown

kra-etims-api-integrationNode.js implementation of the KRA eTIMS API integration.APIKEInactive since 2025Licence unknown

laravel-zatcaLaravel package that generates and signs the QR code for ZATCA e-invoices in Saudi Arabia.APISAInactive since 2021

laravel-zatca-phase2Laravel package for Saudi Arabia's ZATCA Phase 2 e-invoicing.APISAInactive since 2025

m2-vatfallbackMagento 2 module that validates VAT numbers by API, with an offline regex fallback for VIES outages.APIEU · UKArchived

myinvois-gatewayREST gateway that converts JSON to UBL, signs and submits documents to Malaysia's MyInvois clearance API.APIMYInactive since 2025

NAV Online Cash Register logfilePublic repository of the service that downloads Hungarian online cash-register log files.APIHUInactive since 2023

NAV SAF-T HUPublic repository of the Hungarian SAF-T project: schemas and documentation, last changed in 2020.APIHUInactive since 2020

NIP24 PHP clientPHP client for NIP24: validates Polish NIP, REGON and KRS numbers and EU VAT IDs.APIPL · EUNeeds a paid service

node-unipassNode.js client for the Korea Customs Service's Unipass clearance tracking.APIKRInactive since 2025

NormAPI clientTypeScript client for NormAPI: validate and generate XRechnung and ZUGFeRD e-invoices without local Java.APIDENeeds a paid service

oecd (JAXB bindings)Java JAXB classes for the OECD CbC v1 and v2 and CRS schemas, with CTS file packaging and an export tool.APIGlobalInactive since 2024Licence unknown

openadeTypeScript library for Italian electronic receipts (PEM/PEL) and e-invoices to the Revenue Agency's SDI, v0.1.APIITDemo

OxalisOxalis, the open-source Peppol Access Point originally built for the Norwegian government, now frozen.APIEU · NOArchived

peppol-bis-billing-validator (easybill)Docker service that validates XML invoices against the Peppol BIS Billing 3.0 schematron rules.APIEUInactive since 2024

python-a38Python library to create, parse, validate and render Italian electronic invoices (Fattura Elettronica).APIITInactive since 2024

spatie/tax-calculatorPHP interfaces and methods for handling tax calculations in applications.APIGlobalInactive since 2025

Stanza VAT Validator (C#).NET client for a hosted EU and UK VAT number validator and rate lookup.APIEU · UKNeeds a paid service

tax-treaties (LuckStock)Node microservice serving US tax treaty articles and royalty withholding rates, with country reference data.APIUSInactive since 2017

TaxPoynt eInvoiceMiddleware meant to connect financial software to e-invoicing with Nigeria's FIRS; a proof of concept so far.APINGInactive since 2025DemoLicence unknown

UniRate .NET client.NET client for the UniRate API: currency exchange rates and VAT rates by country.APIGlobalNeeds a paid service

vat (Danny van Kooten)Go package that validates EU VAT numbers and looks up VAT rates.APIEUInactive since 2023

viesPHP component that checks EU VAT numbers against the European Commission's VIES service.APIEUInactive since 2024

vies-vat-validation-php-sdk-restPHP SDK for validating VAT numbers through the European Commission's VIES REST service.APIEUInactive since 2023

vies-vat-validation-php-sdk-soapPHP SDK for validating VAT numbers through the European Commission's VIES SOAP service.APIEUInactive since 2023

ZATCA (Android)Android library that generates the ZATCA (Fatoora) e-invoice QR code for POS apps.APISAInactive since 2022Licence unknown

zatca (Axenda)Node.js package that generates the ZATCA (Fatoora) e-invoice QR code for Saudi Arabia.APISAInactive since 2023

zatca (Mrsool)Ruby library to create ZATCA e-invoices and QR codes, supporting Phase 1 and Phase 2.APISAInactive since 2023

zatca-qrPHP implementation of Saudi ZATCA e-invoicing requirements, with QR codes and key and CSR generation.APISAInactive since 2024

zatca-sdk-goGo package that encodes the ZATCA (Fatoora) e-invoice QR code for Saudi Arabia.APISAInactive since 2021

Zatca.Net.NET library that generates the ZATCA e-invoice QR code as hex, base64 or image.APISAInactive since 2022

zoll-api (bund.dev)OpenAPI specification and Python client for German customs (Zoll) import duty and exchange rate queries.APIDEInactive since 2022Licence unknown

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