Sponge
Sponge builds financial infrastructure for the agent economy — wallets that let AI agents hold and spend money, and a gateway that lets businesses sell services directly to agents. The Sponge Wallet API gives an agent its own multi-chain crypto wallet with balances, transfers, swaps, cross-chain bridges, payment links, cards (including a Rain-issued Visa Sponge Card), fiat onramps (Coinbase, Stripe), and trading on Hyperliquid and Polymarket, plus paid access to external services via the x402 and MPP agent-payment protocols. A TypeScript and Python SDK, a spongewallet CLI, and hosted MCP servers ship first-party. Backed by Y Combinator (W2026).
Real signal across most facets with visible, nameable gaps — the contract exists but is thin, or the portal is good while governance and commercial terms are absent.
API Evangelist profiles Sponge the way a machine reads it — 28 machine-readable artifacts across 1 API, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Sponge scores 49.3/100 (developing), with a separate agent-readiness read of 48/100 (agent ready). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance. Every facet and dimension name is a link: it opens that measurement's page on APIs.io, where the rating runs across the whole catalog — the exact checks that feed it, how every profiled provider distributes on it, and who is at the top of it.
Kin Score
How this is scored →scored 2026-09-08 · rubric v0.20.0
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</a>[](https://providers.apievangelist.com/providers/sponge/)<!-- Kin Score · API Evangelist -->
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title="Sponge on API Evangelist — API profile and Kin Score">
<img src="https://apis.io/badge/sponge/card.svg"
alt="Sponge Kin Score — API readiness rating by API Evangelist" width="340" height="120" loading="lazy">
</a>More shapes, themes and sizes → · Score as JSON · How badges work
How we profile Sponge
Each block below is one kind of artifact we hold for Sponge. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 10
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
Individual APIs this provider publishes, each with its own machine-readable definition.
Sponge Agents API
The Agents API from Sponge — 5 operation(s) for agents.
Sponge Cards API
The Cards API from Sponge — 6 operation(s) for cards.
Sponge Fiat API
The Fiat API from Sponge — 11 operation(s) for fiat.
Sponge MPP API
The MPP API from Sponge — 5 operation(s) for mpp.
Sponge Payments API
The Payments API from Sponge — 1 operation(s) for payments.
Sponge Secrets API
The Secrets API from Sponge — 2 operation(s) for secrets.
Sponge Sponge Card API
The Sponge Card API from Sponge — 7 operation(s) for sponge card.
Sponge Trading API
The Trading API from Sponge — 1 operation(s) for trading.
Sponge Transfers API
The Transfers API from Sponge — 9 operation(s) for transfers.
Sponge Wallet API
The Wallet API from Sponge — 4 operation(s) for wallet.
Scroll within the panel for all 10 ·
Open Collections 11
Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.
Open, tool-agnostic API collections (OpenAPI-derived and Bruno).
API Collection
OPEN COLLECTIONSponge public Agents API
OPEN COLLECTIONSponge public Agents Cards API
OPEN COLLECTIONSponge public Agents Fiat API
OPEN COLLECTIONSponge public Agents MPP API
OPEN COLLECTIONSponge public Agents Payments API
OPEN COLLECTIONSponge public Agents Secrets API
OPEN COLLECTIONSponge public Agents Sponge Card API
OPEN COLLECTIONSponge public Agents Trading API
OPEN COLLECTIONSponge public Agents Transfers API
OPEN COLLECTIONSponge public Agents Wallet API
OPEN COLLECTIONScroll within the panel for all 11 ·
Arazzo Workflows 2
Real integrations are rarely a single call. Arazzo describes the multi-step sequences — auth, then create, then confirm — so both a human and an agent can follow the choreography, not just the endpoints.
Multi-step API workflows described with the Arazzo specification.
Sponge — create an agent and issue its key
Platform backend creates a new agent, then mints an agent API key for runtime use.
ARAZZOSponge — check balance, transfer, and confirm
Read wallet balances, send an EVM transfer, then poll transaction status.
ARAZZOMCP Servers 1
Model Context Protocol servers expose these APIs directly to AI agents. We profile them because agent-native access is the fastest-growing way this provider's capabilities actually get used.
Model Context Protocol servers that expose these APIs to AI agents.
Sponge MCP Server
Sponge publishes official, hosted (remote) MCP servers for both the agent Wallet and the merchant Gateway. Wallet servers authenticate with an agent API key (sponge_live_...) fo...
MCP SERVERSecurity Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Scopes 1
OAuth scopes are the vocabulary of least-privilege access. Profiling them shows exactly what an integration — or an agent acting on a user's behalf — is allowed to do.
OAuth scopes governing access to this provider's APIs.
Agentic Access 1
An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.
Recommended x-agentic-access execution contracts for AI agents.
Resources
Every other property we hold for Sponge — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Get Started 4
Portal, sign-up, and the first successful call
Documentation 1
Reference material describing how the API behaves
Agent Surfaces 5
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 6
Pagination, idempotency, versioning, errors, and events
Build 4
SDKs, sample code, and the tooling you integrate with
Access & Security 3
Authentication, authorization, and security posture
Operate 1
Status, limits, changes, and where to get help
Commercial 2
Pricing, plans, and the legal terms of use
Company 1
The organization behind the API
Other 1
Properties that don't map to a standard resource type
← All providers · Data indexed from github.com/api-evangelist/sponge · machine-readable index on apis.io
This is an independent, third-party profile of Sponge, published by API Evangelist. We do not operate, host, resell, or support these APIs, and we are not affiliated with or endorsed by the company unless stated above. Everything here is built from publicly available information — the company's own site, developer portal, documentation, public repositories, and the specifications it publishes for public use. Nothing is obtained by breaching a system, defeating an access control, or using credentials.
The Kin Score and Agent Readiness rating are independently calculated assessments of a company's public API artifacts, scored against a published rubric. They are not certifications, endorsements, security assessments, or audits.
Corrections, re-scores, and removal are free — no partnership or purchase required, and you do not need to justify the request. A removed company is recorded as unrated, never scored zero for having asked. Acknowledgement within one business day; removal within two.
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