Halliday

Halliday is a web3 payments and agentic-workflow company (a16z crypto Series A) building the end-to-end onchain deposit platform. Its Agentic Workflow Protocol (AWP) lets developers compose high-level, AI-executable workflows behind immutable guardrails without writing smart-contract code. The flagship product, Halliday Payments, is a unified cross-chain payments API and drop-in widget that lets users onramp from fiat, bridge, and swap to acquire any asset on any chain in a fully self-custodial way, routing intelligently across onramps (MoonPay, Transak, Stripe), swaps, and bridges. The Halliday API V2 (https://v2.prod.halliday.xyz) exposes chains, assets, quotes, payments, balances, withdrawals, and signed workflow webhooks, authenticated with publishable API keys, alongside JS/React/React Native SDKs and a published Claude Code integration skill.

Halliday publishes 1 API on the APIs.io network: API V2. Tagged areas include Company, Payments, Cryptocurrency, Blockchain, and Web3.

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

Halliday’s developer surface includes documentation, API reference, getting-started guide, support, engineering blog, signup flow, sandbox, and 22 more developer resources.

🌐 Visit website 📡 Source on GitHub

50.5/100 developing Agent 71/100 agent native Full breakdown ↓
scored 2026-07-20 · rubric v0.4

1 APIs 1 MCP Servers 0 Features

CompanyPaymentsCryptocurrencyBlockchainWeb3OnrampSwapsDeFiAgentic WorkflowsFintech

API Rating

API Evangelist Rating How this is scored →
scored 2026-07-20 · rubric v0.4

Composite quality — 50.5/100 · developing

Contract Quality 15.1 / 25

Developer Ergonomics 16.1 / 20

Commercial Clarity 8.4 / 20

Operational Transparency 1.7 / 13

Governance 0.0 / 12

Discoverability 9.3 / 10

Agent readiness — 71/100 · agent native

Machine-Readable Contract 18 / 18

Agentic Access Contract 15 / 15

MCP Server 12 / 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 6 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/halliday: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

Get Started 4

Portal, sign-up, and the first successful call

DeveloperPortal

GettingStarted

SignUp

Sandbox

Documentation 3

Reference material describing how the API behaves

OpenAPI

OpenAPI

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

MCPServer

LLMsTxt

AgentSkill

Design & Contract 7

Pagination, idempotency, versioning, errors, and events

Conformance

ErrorCatalog

Lifecycle

Conventions

Components

DataModel

Webhooks

Scroll for all 7

Build 3

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Packages

Packages

SDKs

SDKs

Access & Security 3

Authentication, authorization, and security posture

Compliance

Compliance

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Support

Support

Commercial 2

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 1

The organization behind the API

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Overlay

Overlay

Source (apis.yml)

aid: halliday
name: Halliday
description: Halliday is a web3 payments and agentic-workflow company (a16z crypto Series A) building the end-to-end onchain
  deposit platform. Its Agentic Workflow Protocol (AWP) lets developers compose high-level, AI-executable workflows behind
  immutable guardrails without writing smart-contract code. The flagship product, Halliday Payments, is a unified cross-chain
  payments API and drop-in widget that lets users onramp from fiat, bridge, and swap to acquire any asset on any chain in
  a fully self-custodial way, routing intelligently across onramps (MoonPay, Transak, Stripe), swaps, and bridges. The Halliday
  API V2 (https://v2.prod.halliday.xyz) exposes chains, assets, quotes, payments, balances, withdrawals, and signed workflow
  webhooks, authenticated with publishable API keys, alongside JS/React/React Native SDKs and a published Claude Code integration
  skill.
url: https://raw.githubusercontent.com/api-evangelist/halliday/refs/heads/main/apis.yml
image: https://halliday.xyz/opengraph-image
x-type: company
x-source: vc-portfolio
x-backed-by:
- a16z
x-tier: profiled
x-tier-reason: enriched-from-portfolio-lead
specificationVersion: '0.20'
created: '2026-07-17'
modified: '2026-07-19'
tags:
- Company
- Payments
- Cryptocurrency
- Blockchain
- Web3
- Onramp
- Swaps
- DeFi
- Agentic Workflows
- Fintech
apis:
- name: Halliday API V2
  description: Unified cross-chain crypto payments API supporting fiat onramps, swaps, and offramps. Quote payments across
    providers, confirm and fund via a One-Time Wallet deposit address, poll payment status/history, check balances, execute
    withdrawals, and receive signed workflow webhooks.
  humanURL: https://docs.halliday.xyz
  baseURL: https://v2.prod.halliday.xyz
  image: https://halliday.xyz/opengraph-image
  tags:
  - Payments
  - Cryptocurrency
  - Onramp
  - Swaps
  - Blockchain
  properties:
  - type: OpenAPI
    url: openapi/halliday-openapi-original.yml
  - type: Documentation
    url: https://docs.halliday.xyz
  - type: APIReference
    url: https://docs.halliday.xyz/pages/halliday-api-docs.md
  - type: GettingStarted
    url: https://docs.halliday.xyz/pages/api-quickstart.md
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: OpenAPI
  url: openapi/halliday-openapi-original.yml
- type: DeveloperPortal
  url: https://docs.halliday.xyz
- type: Documentation
  url: https://docs.halliday.xyz
- type: APIReference
  url: https://docs.halliday.xyz/pages/halliday-api-docs.md
- type: GettingStarted
  url: https://docs.halliday.xyz/pages/api-quickstart.md
- type: Support
  url: https://halliday.xyz/contact
- type: Blog
  url: https://blog.halliday.xyz
- type: GitHubOrganization
  url: https://github.com/HallidayInc
- type: SignUp
  url: https://dashboard.halliday.xyz/
- type: TermsOfService
  url: https://halliday.xyz/legal/terms-of-use
- type: PrivacyPolicy
  url: https://halliday.xyz/legal/privacy-policy
- type: Sandbox
  url: https://demo.halliday.xyz/
- type: Compliance
  url: https://docs.halliday.xyz/pages/compliance-security.md
- type: Authentication
  url: authentication/halliday-authentication.yml
- type: AgenticAccess
  url: agentic-access/halliday-agentic-access.yml
- type: DomainSecurity
  url: security/halliday-domain-security.yml
- type: Packages
  url: packages/halliday-packages.yml
- type: SDKs
  url: packages/halliday-packages.yml
- type: MCPServer
  url: mcp/halliday-mcp.yml
- type: LLMsTxt
  url: llms/halliday-llms.txt
- type: Overlay
  url: overlays/halliday-openapi-overlay.yaml
- type: Conformance
  url: conformance/halliday-conformance.yml
- type: ErrorCatalog
  url: errors/halliday-problem-types.yml
- type: Lifecycle
  url: lifecycle/halliday-lifecycle.yml
- type: Conventions
  url: conventions/halliday-conventions.yml
- type: Components
  url: components/halliday-components.yml
- type: DataModel
  url: data-model/halliday-data-model.yml
- type: Webhooks
  url: asyncapi/halliday-webhooks.yml
- type: AgentSkill
  url: skills/_index.yml
x-enrichment:
  date: '2026-07-19'
  status: backfilled
  pass: local-v1
  note: backfilled from .gitignore signal + verified work evidence

Halliday

API Rating

APIs

Halliday API V2

MCP Servers

halliday-mcp.yml

Event Specifications

Halliday Webhooks

Resources