Cello

Cello is an all-in-one, AI-powered referral platform for SaaS companies. It lets product teams embed in-product user referrals and run partner/affiliate programs with a few lines of code, then automates attribution, campaigns, notifications, fraud detection, and cross-border payouts. Cello ships an embeddable Referral Component and Attribution JS SDK for web plus native iOS, Android, Flutter, and React Native SDKs, a REST API for tokens, referral-code validation, events, and new-user rewards, a Growth Portal for analytics, and an official hosted MCP server exposing developer and growth-manager tools. Customers include Typeform, Miro, Descript, Pleo, and SmallPDF. Backed by HV Capital.

Cello publishes 5 APIs on the APIs.io network, including Events API, New Users API, Referral Codes API, and 2 more. Tagged areas include Company, Referral Marketing, Affiliate Marketing, Growth, and Software-as-a-Service.

Cello’s developer surface includes authentication, documentation, API reference, getting-started guide, support, engineering blog, pricing, and 32 more developer resources.

🌐 Visit website 📡 Source on GitHub

58.9/100 strong ▬ flat Agent 59/100 agent ready Front door AI 3/6 light saas Full breakdown ↓
scored 2026-09-25 · rubric v0.23.0

AccessFreemiumSelf serve

1 APIs 1 MCP Servers

Company Referral Marketing Affiliate Marketing Growth Software-as-a-Service Attribution Partner Programs Ai Enterprise Software A2A

Kin Score

Kin Score How this is scored →
scored 2026-09-25 · rubric v0.23.0

Composite quality — 58.9/100 · strong

Contract Quality 9.6 / 19

Developer Ergonomics 11.8 / 15

Access Clarity 11.6 / 15

Operational Transparency 1.8 / 10

Contract Governance 1.6 / 9

Discoverability 5.6 / 8

Regulatory Posture 5.9 / 15

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 59/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 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 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 6 / 6

Protected Resource Metadata 5 / 5

Registration Without a Human 6 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) 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/cello: 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 5

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

Cello Events API

The Events API from Cello — 1 operation(s) for events.

Cello New Users API

The New Users API from Cello — 1 operation(s) for new users.

Cello Referral Codes API

The Referral Codes API from Cello — 2 operation(s) for referral codes.

Cello Referrers API

The Referrers API from Cello — 1 operation(s) for referrers.

Cello Token API

The Token API from Cello — 1 operation(s) for token.

Open Collections 6

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

API Collection

OPEN COLLECTION

Cello Events API

OPEN COLLECTION

Cello Events New Users API

OPEN COLLECTION

Cello Events Referral Codes API

OPEN COLLECTION

Cello Events Referrers API

OPEN COLLECTION

Cello Events Token API

OPEN COLLECTION

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

Cello MCP Server

MCP SERVER

Pricing Plans 1

Published pricing tiers and plan structures.

Cello Plans Pricing

7 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Cello Rate Limits

0 limits

RATE LIMITS

Security Posture 2

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

Cello Authentication

http/oauth2 · 3 schemes

SECURITY

Cello Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Scopes 1

OAuth scopes governing access to this provider's APIs.

Cello Scopes

OAuth 2.0 · no documented scopes

0 scopes

SCOPES

Agentic Access 1

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

Cello Agentic Access

6 operations · 3 acting

AGENTIC

Resources

Get Started 4

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

Login

Sandbox

Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 7

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

MCPServer

LLMsTxt

AgentSkill

AgentSkill

AgentSkill

WellKnown

Scroll for all 7

Design & Contract 6

Pagination, idempotency, versioning, errors, and events

Components

Lifecycle

Conventions

ErrorCatalog

DataModel

Conformance

Build 4

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

Packages

SDKs

ToolCrosswalk

Access & Security 4

Authentication, authorization, and security posture

DomainSecurity

Authentication

Compliance

OAuthScopes

Operate 4

Status, limits, changes, and where to get help

Support

ChangeLog

RateLimits

Contact

Commercial 4

Pricing, plans, and the legal terms of use

Pricing

TermsOfService

PrivacyPolicy

Plans

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 2

Properties that don't map to a standard resource type

Overlay

Overlay

AgentCard

AgentCard

Source (apis.yml)

aid: cello
name: Cello
description: Cello is an all-in-one, AI-powered referral platform for SaaS companies. It lets product teams embed in-product
  user referrals and run partner/affiliate programs with a few lines of code, then automates attribution, campaigns, notifications,
  fraud detection, and cross-border payouts. Cello ships an embeddable Referral Component and Attribution JS SDK for web plus
  native iOS, Android, Flutter, and React Native SDKs, a REST API for tokens, referral-code validation, events, and new-user
  rewards, a Growth Portal for analytics, and an official hosted MCP server exposing developer and growth-manager tools. Customers
  include Typeform, Miro, Descript, Pleo, and SmallPDF. Backed by HV Capital.
url: https://raw.githubusercontent.com/api-evangelist/cello/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: freemium
  onboarding: self-serve
  trial: false
  try_now: false
  public: false
  label: Self-serve signup
  confidence: high
  source:
  - authentication
  - plans
  generated: '2026-08-13'
  method: searched
  note: List pricing is published for both product lines. Partner Referrals has a $0/mo Free tier (1 campaign, 10 partners);
    User Referrals starts at $200/mo and is metered on referral ARR, not API calls. No tier gates API, SDK or MCP access.
image: https://cello.so/wp-content/uploads/2022/12/Group-174900-1.png
x-type: company
x-source: vc-portfolio
x-backed-by:
- hv-capital
x-tier: stub
x-tier-reason: portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-08-13'
x-docs-platform: mintlify
x-docs-platform-confidence: medium
x-docs-platform-checked: 2026-09-21
x-docs-hosting: vercel
tags:
- Company
- Referral Marketing
- Affiliate Marketing
- Growth
- Software-as-a-Service
- Attribution
- Partner Programs
- Ai Enterprise Software
- A2A
tags_raw:
- Company
- Referral Marketing
- Affiliate Marketing
- Growth
- SaaS
- Attribution
- Partner Programs
- Ai Enterprise Software
- A2A
apis:
- aid: cello:cello-events-api
  name: Cello Events API
  description: The Events API from Cello — 1 operation(s) for events.
  humanURL: https://docs.cello.so/api-reference/introduction
  baseURL: https://api.cello.so
  tags:
  - Event
  tags_raw:
  - Events
  properties:
  - type: OpenAPI
    url: openapi/cello-events-api-openapi.yml
- aid: cello:cello-new-users-api
  name: Cello New Users API
  description: The New Users API from Cello — 1 operation(s) for new users.
  humanURL: https://docs.cello.so/api-reference/introduction
  baseURL: https://api.cello.so
  tags:
  - New Users
  properties:
  - type: OpenAPI
    url: openapi/cello-new-users-api-openapi.yml
- aid: cello:cello-referral-codes-api
  name: Cello Referral Codes API
  description: The Referral Codes API from Cello — 2 operation(s) for referral codes.
  humanURL: https://docs.cello.so/api-reference/introduction
  baseURL: https://api.cello.so
  tags:
  - Referral Codes
  properties:
  - type: OpenAPI
    url: openapi/cello-referral-codes-api-openapi.yml
- aid: cello:cello-referrers-api
  name: Cello Referrers API
  description: The Referrers API from Cello — 1 operation(s) for referrers.
  humanURL: https://docs.cello.so/api-reference/introduction
  baseURL: https://api.cello.so
  tags:
  - Referrers
  properties:
  - type: OpenAPI
    url: openapi/cello-referrers-api-openapi.yml
- aid: cello:cello-token-api
  name: Cello Token API
  description: The Token API from Cello — 1 operation(s) for token.
  humanURL: https://docs.cello.so/api-reference/introduction
  baseURL: https://api.cello.so
  tags:
  - Tokens
  tags_raw:
  - Token
  properties:
  - type: OpenAPI
    url: openapi/cello-token-api-openapi.yml
common:
- type: Website
  url: https://www.cello.so/
- type: Overlay
  url: overlays/cello-openapi-overlay.yaml
- type: DomainSecurity
  url: security/cello-domain-security.yml
- type: AgenticAccess
  url: agentic-access/cello-agentic-access.yml
- type: Authentication
  url: authentication/cello-authentication.yml
- type: DeveloperPortal
  url: https://docs.cello.so
- type: Documentation
  url: https://docs.cello.so
- type: APIReference
  url: https://docs.cello.so/api-reference/introduction
- type: GettingStarted
  url: https://docs.cello.so/integration-overview
- type: Support
  url: https://docs.cello.so/guides/support/faqs
- type: Blog
  url: https://cello.so/resources/
- type: GitHubOrganization
  url: https://github.com/getcello
- type: Pricing
  url: https://cello.so/pricing/
- type: Login
  url: https://portal.cello.so
- type: TermsOfService
  url: https://cello.so/terms-of-service/
- type: PrivacyPolicy
  url: https://cello.so/privacy-policy/
- type: MCPServer
  url: mcp/cello-mcp.yml
- type: LLMsTxt
  url: llms/cello-llms.txt
- type: Packages
  url: packages/cello-packages.yml
- type: SDKs
  url: packages/cello-packages.yml
- type: Components
  url: components/cello-components.yml
- type: Sandbox
  url: sandbox/cello-sandbox.yml
- type: ChangeLog
  url: changelog/cello-changelog.yml
- type: Lifecycle
  url: lifecycle/cello-lifecycle.yml
- type: Conventions
  url: conventions/cello-conventions.yml
- type: ErrorCatalog
  url: errors/cello-problem-types.yml
- type: DataModel
  url: data-model/cello-data-model.yml
- type: Conformance
  url: conformance/cello-conformance.yml
- type: Compliance
  url: https://cello.so/privacy-policy/
- type: AgentSkill
  url: skills/cello-track-referral-conversion.md
- type: AgentSkill
  url: skills/cello-fetch-and-reward-referee.md
- type: AgentSkill
  url: skills/cello-referral-integration.md
- type: AgentCard
  url: a2a/cello-a2a.yml
- type: WellKnown
  url: well-known/cello-well-known.yml
- type: OAuthScopes
  url: scopes/cello-scopes.yml
- type: ToolCrosswalk
  url: mcp/cello-tool-crosswalk.yml
- type: Plans
  url: plans/cello-plans-pricing.yml
- type: RateLimits
  url: rate-limits/cello-rate-limits.yml
- type: Contact
  url: mailto:support@cello.so
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
x-enrichment:
  date: '2026-08-13'
  status: enriched
  artifacts_added: 11
  pass: local-v1

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