Overflow

Overflow is a fintech giving platform for churches and nonprofits that lets organizations accept and reconcile donations across many asset types — card and ACH, Apple Pay and Google Pay, stock, cryptocurrency, RoundUps, and Donor Advised Funds (DAFs) — through a single unified platform. Overflow also offers Overflow Tap (NFC tap-to-give hardware) and Generosity University donor education. Its public Overflow Open API (v3) is a REST interface over contributions, donors, subscriptions (recurring gifts), payments, campaigns, deposits, refunds, chargebacks, locations, tap devices/events, and webhooks, authenticated with header API keys and used to sync giving data into CRMs and accounting/reconciliation workflows. Overflow is backed by Uncork Capital.

Overflow publishes 13 APIs on the APIs.io network, including Campaigns API, Chargebacks API, Contributions API, and 10 more. Tagged areas include Company, Fintech, Payments, Donations, and Fundraising.

The Overflow catalog on APIs.io includes 1 event-driven AsyncAPI specification.

Overflow’s developer surface includes documentation, API reference, getting-started guide, authentication, engineering blog, signup flow, sandbox, and 20 more developer resources.

🌐 Visit website 📡 Source on GitHub

46.1/100 developing ▬ flat Agent 32/100 agent ready saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

1 APIs

Company Fintech Payments Donations Fundraising Non-Profit Giving Recurring Payments Webhook Cryptocurrency

Kin Score

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

Composite quality — 46.1/100 · developing

Contract Quality 11.3 / 19

Developer Ergonomics 9.2 / 15

Access Clarity 5.1 / 15

Operational Transparency 2.6 / 10

Contract Governance 0.4 / 9

Discoverability 5.7 / 8

Regulatory Posture 5.9 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 32/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 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 applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

The six quality facets above are damped to 75 points between them, because the conditional facet above carries the other 25. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% 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/overflow: 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 13

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

Overflow Campaigns API

The Campaigns API from Overflow — 2 operation(s) for campaigns.

Overflow Chargebacks API

The Chargebacks API from Overflow — 2 operation(s) for chargebacks.

Overflow Contributions API

The Contributions API from Overflow — 3 operation(s) for contributions.

Overflow Deposits API

The Deposits API from Overflow — 3 operation(s) for deposits.

Overflow Donors API

The Donors API from Overflow — 2 operation(s) for donors.

Overflow Locations API

The Locations API from Overflow — 2 operation(s) for locations.

Overflow Payment Methods API

The Payment Methods API from Overflow — 1 operation(s) for payment methods.

Overflow Payments API

The Payments API from Overflow — 1 operation(s) for payments.

Overflow Refunds API

The Refunds API from Overflow — 2 operation(s) for refunds.

Overflow Status API

The Status API from Overflow — 1 operation(s) for status.

Overflow Subscriptions API

The Subscriptions API from Overflow — 3 operation(s) for subscriptions.

Overflow Tap API

The Tap API from Overflow — 7 operation(s) for tap.

Overflow Webhooks API

The Webhooks API from Overflow — 3 operation(s) for webhooks.

Scroll for all 13

Open Collections 14

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

Overflow Open Campaigns API

OPEN COLLECTION

Overflow Open Campaigns Chargebacks API

OPEN COLLECTION

Overflow Open Campaigns Contributions API

OPEN COLLECTION

Overflow Open Campaigns Deposits API

OPEN COLLECTION

Overflow Open Campaigns Donors API

OPEN COLLECTION

Overflow Open Campaigns Locations API

OPEN COLLECTION

Overflow Open Campaigns Payment Methods API

OPEN COLLECTION

Overflow Open Campaigns Payments API

OPEN COLLECTION

Overflow Open Campaigns Refunds API

OPEN COLLECTION

Overflow Open Campaigns Status API

OPEN COLLECTION

Overflow Open Campaigns Subscriptions API

OPEN COLLECTION

Overflow Open Campaigns Tap API

OPEN COLLECTION

Overflow Open Campaigns Webhooks API

OPEN COLLECTION

Scroll for all 14

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Overflow Webhooks

ASYNCAPI

Security Posture 2

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

Overflow Authentication

apiKey · 2 schemes

SECURITY

Overflow Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Overflow Agentic Access

38 operations · 8 acting · 8 human-in-the-loop

38 operations · 8 acting

AGENTIC

Resources

Get Started 5

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

SignUp

SignUp

Login

Sandbox

Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt

LLMsTxt

X-MCPServerCandidate

X-MCPServerCandidate

AgenticAccess

AgenticAccess

AgentSkill

AgentSkill

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

Webhooks

Conformance

ErrorCatalog

Lifecycle

Conventions

DataModel

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 2

Status, limits, changes, and where to get help

RateLimits

RateLimits

StatusPage

StatusPage

Commercial 2

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Overlay

Overlay

Source (apis.yml)

aid: overflow
name: Overflow
description: Overflow is a fintech giving platform for churches and nonprofits that lets organizations accept and reconcile
  donations across many asset types — card and ACH, Apple Pay and Google Pay, stock, cryptocurrency, RoundUps, and Donor Advised
  Funds (DAFs) — through a single unified platform. Overflow also offers Overflow Tap (NFC tap-to-give hardware) and Generosity
  University donor education. Its public Overflow Open API (v3) is a REST interface over contributions, donors, subscriptions
  (recurring gifts), payments, campaigns, deposits, refunds, chargebacks, locations, tap devices/events, and webhooks, authenticated
  with header API keys and used to sync giving data into CRMs and accounting/reconciliation workflows. Overflow is backed
  by Uncork Capital.
url: https://raw.githubusercontent.com/api-evangelist/overflow/refs/heads/main/apis.yml
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - 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://cdn.prod.website-files.com/661982b7ce6b433411c6e0c8/661986ff805671631abc51f8_Open%20Graph%20Image.webp
x-type: company
x-source: vc-portfolio
x-backed-by:
- uncork-capital
x-tier: stub
x-tier-reason: portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-20'
tags:
- Company
- Fintech
- Payments
- Donations
- Fundraising
- Non-Profit
- Giving
- Recurring Payments
- Webhook
- Cryptocurrency
tags_raw:
- Company
- Fintech
- Payments
- Donations
- Fundraising
- Nonprofit
- Giving
- Recurring Payments
- Webhooks
- Cryptocurrency
apis:
- aid: overflow:overflow-campaigns-api
  name: Overflow Campaigns API
  description: The Campaigns API from Overflow — 2 operation(s) for campaigns.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Campaigns
  properties:
  - type: OpenAPI
    url: openapi/overflow-campaigns-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-chargebacks-api
  name: Overflow Chargebacks API
  description: The Chargebacks API from Overflow — 2 operation(s) for chargebacks.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Chargebacks
  properties:
  - type: OpenAPI
    url: openapi/overflow-chargebacks-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-contributions-api
  name: Overflow Contributions API
  description: The Contributions API from Overflow — 3 operation(s) for contributions.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Contributions
  properties:
  - type: OpenAPI
    url: openapi/overflow-contributions-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-deposits-api
  name: Overflow Deposits API
  description: The Deposits API from Overflow — 3 operation(s) for deposits.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Deposits
  properties:
  - type: OpenAPI
    url: openapi/overflow-deposits-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-donors-api
  name: Overflow Donors API
  description: The Donors API from Overflow — 2 operation(s) for donors.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Donors
  properties:
  - type: OpenAPI
    url: openapi/overflow-donors-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-locations-api
  name: Overflow Locations API
  description: The Locations API from Overflow — 2 operation(s) for locations.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Locations
  properties:
  - type: OpenAPI
    url: openapi/overflow-locations-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-payment-methods-api
  name: Overflow Payment Methods API
  description: The Payment Methods API from Overflow — 1 operation(s) for payment methods.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Payment Methods
  properties:
  - type: OpenAPI
    url: openapi/overflow-payment-methods-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-payments-api
  name: Overflow Payments API
  description: The Payments API from Overflow — 1 operation(s) for payments.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Payments
  properties:
  - type: OpenAPI
    url: openapi/overflow-payments-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-refunds-api
  name: Overflow Refunds API
  description: The Refunds API from Overflow — 2 operation(s) for refunds.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Refunds
  properties:
  - type: OpenAPI
    url: openapi/overflow-refunds-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-status-api
  name: Overflow Status API
  description: The Status API from Overflow — 1 operation(s) for status.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Status
  properties:
  - type: OpenAPI
    url: openapi/overflow-status-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-subscriptions-api
  name: Overflow Subscriptions API
  description: The Subscriptions API from Overflow — 3 operation(s) for subscriptions.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Subscription
  tags_raw:
  - Subscriptions
  properties:
  - type: OpenAPI
    url: openapi/overflow-subscriptions-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-tap-api
  name: Overflow Tap API
  description: The Tap API from Overflow — 7 operation(s) for tap.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - TAP
  tags_raw:
  - Tap
  properties:
  - type: OpenAPI
    url: openapi/overflow-tap-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
- aid: overflow:overflow-webhooks-api
  name: Overflow Webhooks API
  description: The Webhooks API from Overflow — 3 operation(s) for webhooks.
  humanURL: https://docs.overflow.co/api-reference/welcome
  baseURL: https://server.overflow.co
  tags:
  - Webhook
  tags_raw:
  - Webhooks
  properties:
  - type: OpenAPI
    url: openapi/overflow-webhooks-api-openapi.yml
  - type: Documentation
    url: https://docs.overflow.co/api-reference/welcome
  - type: APIReference
    url: https://docs.overflow.co/api-reference/welcome
  - type: Authentication
    url: authentication/overflow-authentication.yml
  - type: Webhooks
    url: asyncapi/overflow-webhooks.yml
x-enrichment:
  date: '2026-07-20'
  status: enriched
  artifacts_added: 16
  pass: local-v1
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://www.overflow.co/
- type: DeveloperPortal
  url: https://docs.overflow.co
- type: Documentation
  url: https://docs.overflow.co
- type: APIReference
  url: https://docs.overflow.co/api-reference/welcome
- type: GettingStarted
  url: https://docs.overflow.co/api-reference/quickstart
- type: Authentication
  url: authentication/overflow-authentication.yml
- type: RateLimits
  url: https://docs.overflow.co/api-reference/rate-limiting
- type: Webhooks
  url: asyncapi/overflow-webhooks.yml
- type: StatusPage
  url: https://status.overflow.co
- type: Blog
  url: https://www.overflow.co/learn
- type: GitHubOrganization
  url: https://github.com/overflow-co
- type: SignUp
  url: https://dashboard.overflow.co/login
- type: Login
  url: https://dashboard.overflow.co/login
- type: TermsOfService
  url: https://www.overflow.co/terms
- type: PrivacyPolicy
  url: https://www.overflow.co/privacy
- type: LLMsTxt
  url: llms/overflow-llms.txt
- type: X-MCPServerCandidate
  url: mcp/overflow-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: Overlay
  url: overlays/overflow-openapi-overlay.yaml
- type: Conformance
  url: conformance/overflow-conformance.yml
- type: ErrorCatalog
  url: errors/overflow-problem-types.yml
- type: Lifecycle
  url: lifecycle/overflow-lifecycle.yml
- type: DomainSecurity
  url: security/overflow-domain-security.yml
- type: Conventions
  url: conventions/overflow-conventions.yml
- type: Sandbox
  url: sandbox/overflow-sandbox.yml
- type: DataModel
  url: data-model/overflow-data-model.yml
- type: AgenticAccess
  url: agentic-access/overflow-agentic-access.yml
- type: AgentSkill
  url: skills/_index.yml

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