String Technology Inc

String (string.xyz) is a fiat interoperability platform for Web3 gaming, operated by String Technology Inc and backed by 500 Global. String lets game developers accept credit-card and bank payments natively inside their games, acting as the merchant of record and counterparty for fiat on/off ramps, NFT purchases, and cross-chain payments. A player pays fiat on traditional rails and String delivers the digital asset on-chain — either by interacting with the game's smart contract to mint/send an NFT or by sending a token from its treasury to the player's wallet. String ships three integration surfaces — String Checkout (drop-in payment app), a Unity SDK, and String Direct (custom web SDK) — all wrapping a REST API at string-api.xyz that covers API keys, contracts, platforms (games), members, organizations, users (players), saved cards, wallet-signature login, quotes, and transactions.

String Technology Inc publishes 1 API on the APIs.io network. Tagged areas include Company, Payments, Web3, Gaming, and Fiat On-Ramp.

String Technology Inc’s developer surface includes documentation, API reference, getting-started guide, signup flow, sandbox, authentication, and 15 more developer resources.

🌐 Visit website 📡 Source on GitHub

18.3/100 emerging ▬ flat Agent 6/100 agent aware saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

1 APIs

Company Payments Web3 GamingFiat On-RampCryptocurrency NFT Merchant of Record Developer Tools

Kin Score

Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0

Composite quality — 18.3/100 · emerging

Contract Quality 0.0 / 21

Developer Ergonomics 8.0 / 17

Access Clarity 1.1 / 17

Operational Transparency 0.3 / 11

Contract Governance 0.5 / 10

Discoverability 6.5 / 9

Regulatory Posture 4.0 / 15

Agent readiness — 6/100 · agent aware

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Payments regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/string-technology-inc: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 1

Individual APIs this provider publishes, each with its own machine-readable definition.

String API

REST API for String's fiat-for-Web3-gaming platform — quotes and transactions (fiat on/off ramp, NFT purchase, cross-chain), plus management of API keys, contracts, platforms (g...

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

String Technology Inc Authentication

apiKey/walletSignature/session · 4 schemes

SECURITY

String Technology Inc Domain Security

TLSv1.3 · HSTS

SECURITY

Resources

Get Started 4

Portal, sign-up, and the first successful call

DeveloperPortal

GettingStarted

SignUp

Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

X-MCPServerCandidate

X-MCPServerCandidate

AgentSkill

AgentSkill

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

Components

ErrorCatalog

Conventions

Conformance

Lifecycle

DataModel

Build 3

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Packages

Packages

SDKs

SDKs

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Company 1

The organization behind the API

Website

Website

Source (apis.yml)

aid: string-technology-inc
name: String Technology Inc
description: String (string.xyz) is a fiat interoperability platform for Web3 gaming, operated by String Technology Inc and
  backed by 500 Global. String lets game developers accept credit-card and bank payments natively inside their games, acting
  as the merchant of record and counterparty for fiat on/off ramps, NFT purchases, and cross-chain payments. A player pays
  fiat on traditional rails and String delivers the digital asset on-chain — either by interacting with the game's smart contract
  to mint/send an NFT or by sending a token from its treasury to the player's wallet. String ships three integration surfaces
  — String Checkout (drop-in payment app), a Unity SDK, and String Direct (custom web SDK) — all wrapping a REST API at string-api.xyz
  that covers API keys, contracts, platforms (games), members, organizations, users (players), saved cards, wallet-signature
  login, quotes, and transactions.
url: https://raw.githubusercontent.com/api-evangelist/string-technology-inc/refs/heads/main/apis.yml
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - security
  - sandbox
  generated: '2026-09-03'
  method: derived
image: https://avatars.githubusercontent.com/u/104804397?v=4
x-type: company
x-source: vc-portfolio
x-backed-by:
- 500-global
x-tier: stub
x-tier-reason: portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-21'
tags:
- Company
- Payments
- Web3
- Gaming
- Fiat On-Ramp
- Cryptocurrency
- NFT
- Merchant of Record
- Developer Tools
apis:
- name: String API
  description: REST API for String's fiat-for-Web3-gaming platform — quotes and transactions (fiat on/off ramp, NFT purchase,
    cross-chain), plus management of API keys, contracts, platforms (games), members, organizations, users (players), saved
    cards, and wallet-signature authentication.
  humanURL: https://docs.string.xyz
  baseURL: https://string-api.xyz
  tags:
  - Payments
  - Web3
  - Gaming
  properties:
  - type: Documentation
    url: https://docs.string.xyz
  - type: APIReference
    url: https://docs.string.xyz/reference/get_apikeys
  - type: GettingStarted
    url: https://docs.string.xyz/docs/getting-started
  - type: LLMsTxt
    url: llms/string-technology-inc-llms.txt
  - type: Authentication
    url: authentication/string-technology-inc-authentication.yml
  - type: ErrorCatalog
    url: errors/string-technology-inc-problem-types.yml
  - type: Conventions
    url: conventions/string-technology-inc-conventions.yml
  - type: Conformance
    url: conformance/string-technology-inc-conformance.yml
  - type: Lifecycle
    url: lifecycle/string-technology-inc-lifecycle.yml
  - type: DataModel
    url: data-model/string-technology-inc-data-model.yml
  - type: X-MCPServerCandidate
    url: mcp/string-technology-inc-mcp.yml
    note: 'Renamed from MCPServer 2026-09-03 (roadmap#247): the manifest self-describes as status: candidate — a tool list
      derived from the published API contracts, not an existing server. The scorer already read the manifest and reported
      mcp_server correctly; the MCPServer type was crediting the artifact-type surfaces with a server that does not exist.'
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://string.xyz
- type: DeveloperPortal
  url: https://docs.string.xyz
- type: Documentation
  url: https://docs.string.xyz
- type: APIReference
  url: https://docs.string.xyz/reference/get_apikeys
- type: GettingStarted
  url: https://docs.string.xyz/docs/getting-started
- type: GitHubOrganization
  url: https://github.com/String-xyz
- type: SignUp
  url: https://sandbox.string.xyz/login
- type: Sandbox
  url: sandbox/string-technology-inc-sandbox.yml
- type: LLMsTxt
  url: llms/string-technology-inc-llms.txt
- type: Packages
  url: packages/string-technology-inc-packages.yml
- type: SDKs
  url: packages/string-technology-inc-packages.yml
- type: Components
  url: components/string-technology-inc-components.yml
- type: Authentication
  url: authentication/string-technology-inc-authentication.yml
- type: ErrorCatalog
  url: errors/string-technology-inc-problem-types.yml
- type: Conventions
  url: conventions/string-technology-inc-conventions.yml
- type: Conformance
  url: conformance/string-technology-inc-conformance.yml
- type: Lifecycle
  url: lifecycle/string-technology-inc-lifecycle.yml
- type: DataModel
  url: data-model/string-technology-inc-data-model.yml
- type: X-MCPServerCandidate
  url: mcp/string-technology-inc-mcp.yml
  note: 'Renamed from MCPServer 2026-09-03 (roadmap#247): the manifest self-describes as status: candidate — a tool list derived
    from the published API contracts, not an existing server. The scorer already read the manifest and reported mcp_server
    correctly; the MCPServer type was crediting the artifact-type surfaces with a server that does not exist.'
- type: DomainSecurity
  url: security/string-technology-inc-domain-security.yml
- type: AgentSkill
  url: skills/_index.yml
x-enrichment:
  date: '2026-07-21'
  status: enriched
  artifacts_added: 15
  pass: local-v1

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