aid: stax
name: Stax
description: Stax (formerly Fattmerchant) is an Orlando, Florida payments technology company that sells subscription-priced
  payment processing to small and large merchants (Stax Pay), embedded payments and merchant onboarding to SaaS
  platforms and ISVs (Stax Connect), compliant credit-card surcharging (CardX by Stax), automated subscription billing
  (Stax Bill), and full-stack processing for partners and ISOs (Stax Processing). Its public REST API at apiprod.fattlabs.com
  covers charges, credits, refunds and voids, stored payment methods and tokenization, customers, invoices and invoice
  schedules, payment links, catalog items, terminals and card-present devices, merchant enrollment and underwriting,
  disputes, statements and deposit reporting, teams, users and API keys, and merchant- and partner-level webhooks.
  Stax.js handles browser tokenization; iOS and Android SDKs cover card-present and Tap to Pay. Stax Payments, Inc.
  is a registered ISO/MSP of Fifth Third Bank and Synovus Bank and a registered partner/ISO of Elavon, Inc.
url: https://raw.githubusercontent.com/api-evangelist/stax/refs/heads/main/apis.yml
x-type: company
x-source: harvest:secondary-market
x-tier: profiled
x-tier-reason: enrichment
specificationVersion: '0.20'
created: '2026-08-29'
modified: '2026-08-29'
tags:
- Payments
- Payment Processing
- Merchant Services
- Embedded Payments
- ACH
- Invoicing
- Subscription Billing
- Surcharging
- Point-of-Sale
- Tokenization
- Financial-Services
- Fintech
- Card Present
- Merchant Onboarding
tags_raw:
- Payments
- Payment Processing
- Merchant Services
- Embedded Payments
- ACH
- Invoicing
- Subscription Billing
- Surcharging
- Point of Sale
- Tokenization
- Financial Services
- Fintech
- Card Present
- Merchant Onboarding
apis:
- name: Stax API
  description: The Stax REST API (published as "stax-api") exposes 133 operations across 101 paths at https://apiprod.fattlabs.com
    — the Merchant API for payments, payment methods, customers, invoices, payment links, catalog, terminals, transactions
    and webhooks, and the Partner API for merchant creation, enrollment, registration data, API-key issuance, disputes
    and partner-brand webhooks. Authentication is a bearer API key; sandbox and live keys use the same base URL.
  humanURL: https://docs.staxpayments.com/reference/overview
  baseURL: https://apiprod.fattlabs.com
  image: https://staxpayments.com/wp-content/uploads/2024/04/stax-logo-full.png
  tags:
  - Payments
  - Invoicing
  - Merchant Onboarding
  - Webhook
  - Terminals
  tags_raw:
  - Payments
  - Invoicing
  - Merchant Onboarding
  - Webhooks
  - Terminals
  properties:
  - type: OpenAPI
    url: openapi/stax-api-openapi.json
  - type: Overlay
    url: overlays/stax-api-overlay.yaml
  - type: Documentation
    url: https://docs.staxpayments.com/
  - type: APIReference
    url: https://docs.staxpayments.com/reference/overview
  - type: Examples
    url: examples/stax-api-examples.yml
  - type: DataModel
    url: data-model/stax-data-model.yml
  - type: ErrorCatalog
    url: errors/stax-problem-types.yml
  - type: Webhooks
    url: asyncapi/stax-webhooks.yml
  - type: AgenticAccess
    url: agentic-access/stax-agentic-access.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: AgenticAccess
  url: agentic-access/stax-agentic-access.yml
- type: Website
  url: https://staxpayments.com/
- type: DeveloperPortal
  url: https://docs.staxpayments.com/
- type: Documentation
  url: https://docs.staxpayments.com/
- type: APIReference
  url: https://docs.staxpayments.com/reference/overview
- type: GettingStarted
  url: https://docs.staxpayments.com/docs/getting-started
- type: Support
  url: https://support.fattmerchant.com/
- type: Blog
  url: https://staxpayments.com/blog/
- type: GitHubOrganization
  url: https://github.com/fattmerchantorg
- type: Pricing
  url: https://staxpayments.com/pricing/
- type: SignUp
  url: https://staxpayments.com/request-sandbox/
- type: Login
  url: https://app.staxpayments.com/
- type: TermsOfService
  url: https://staxpayments.com/terms-of-use/
- type: PrivacyPolicy
  url: https://staxpayments.com/privacy/
- type: StatusPage
  url: https://status.staxpayments.com/
- type: ChangeLog
  url: changelog/stax-changelog.yml
- type: Lifecycle
  url: lifecycle/stax-lifecycle.yml
- type: Authentication
  url: authentication/stax-authentication.yml
- type: Conventions
  url: conventions/stax-conventions.yml
- type: Idempotency
  url: conventions/stax-conventions.yml
- type: RateLimits
  url: rate-limits/stax-rate-limits.yml
- type: Plans
  url: plans/stax-plans-pricing.yml
- type: ErrorCatalog
  url: errors/stax-problem-types.yml
- type: DeclineCodes
  url: errors/stax-decline-codes.yml
- type: Webhooks
  url: asyncapi/stax-webhooks.yml
- type: MCPServer
  url: mcp/stax-mcp.yml
- type: ToolCrosswalk
  url: mcp/stax-tool-crosswalk.yml
- type: LLMsTxt
  url: llms/stax-llms.txt
- type: Packages
  url: packages/stax-packages.yml
- type: SDKs
  url: packages/stax-packages.yml
- type: Components
  url: components/stax-components.yml
- type: Sandbox
  url: sandbox/stax-sandbox.yml
- type: DataModel
  url: data-model/stax-data-model.yml
- type: Conformance
  url: conformance/stax-conformance.yml
- type: Compliance
  url: conformance/stax-conformance.yml
- type: TrustCenter
  url: security/stax-trust-center.yml
- type: SecurityTxt
  url: well-known/stax-security.txt
- type: VulnerabilityDisclosure
  url: security/stax-vulnerability-disclosure.yml
- type: Security
  url: security/stax-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/stax-domain-security.yml
- type: AgentSkill
  url: skills/_index.yml
- type: Examples
  url: examples/stax-api-examples.yml
- type: Overlay
  url: overlays/stax-api-overlay.yaml
- type: OpenAPI
  url: openapi/stax-api-openapi.json
image: https://staxpayments.com/wp-content/uploads/2024/04/stax-logo-full.png
x-enrichment:
  date: '2026-08-29'
  status: enriched
  artifacts_added: 33
  pass: local-v1