# Circle Gateway Nanopayments vs Skyfire API + MCP

> Circle Gateway Nanopayments scores 67.6 (B) to Skyfire's 40.3 (E) for stablecoin payments. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-skyfire
- Markdown: https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-skyfire.md (~2,400 tokens)
- Slim: https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-skyfire.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-skyfire.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-09

Circle Gateway Nanopayments scores 67.6 (B) on agent readiness against Skyfire API + MCP's 40.3 (E), and leads in every scored category. Both do stablecoin payments.

- Circle Gateway Nanopayments: grade B, 67.6/100, rank #247 of 950. Markdown https://www.anchorterminal.com/tools/circle-gateway-nanopayments.md · JSON https://www.anchorterminal.com/api/v1/tools/circle-gateway-nanopayments.json
- Skyfire API + MCP: grade E, 40.3/100, rank #911 of 950. Markdown https://www.anchorterminal.com/tools/skyfire.md · JSON https://www.anchorterminal.com/api/v1/tools/skyfire.json
- Best payment and monetisation platforms for AI agents: https://www.anchorterminal.com/best/payment-platforms/index.md
- All 76 platforms comparisons: https://www.anchorterminal.com/compare/payment-platforms/index.md

## Which one, for what

### Circle Gateway Nanopayments (B)

Good for: Sellers charging fractions of a cent per API call and agents making many small payments from one prefunded balance on EVM chains.

Ahead on:
- Reliability, 56 against 19
- Schema & documentation, 80 against 59
- Agent ergonomics, 75 against 61
- Security & auth, 64 against 41
- Payments & pricing, 80 against 20
- Maintenance & community, 77 against 31
- Transparency & trust, 72 against 53

Also in its favour:
- No key needed to call it

Watch for: No rate limit, 429 guidance or SLA was found for the Gateway API in the reviewed documentation

### Skyfire API + MCP (E)

Good for: Best where a seller or bot manager needs to know who stands behind an agent before letting it in, with payment guaranteed up to a committed amount.

Also in its favour:
- No incidents deducted, where Circle Gateway Nanopayments loses 3 points for them

Watch for: No x402 or MPP; both buyer and seller must be on Skyfire


## Score by category

| Category | Weight | Circle Gateway Nanopayments | Skyfire API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 56 | 19 | Circle Gateway Nanopayments +37 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 80 | 59 | Circle Gateway Nanopayments +21 |
| Agent ergonomics | 13% (16.2 this run) | 75 | 61 | Circle Gateway Nanopayments +14 |
| Security & auth | 14% (17.5 this run) | 64 | 41 | Circle Gateway Nanopayments +23 |
| Payments & pricing | 10% (12.5 this run) | 80 | 20 | Circle Gateway Nanopayments +60 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 77 | 31 | Circle Gateway Nanopayments +46 |
| Transparency & trust | 7% (8.8 this run) | 72 | 53 | Circle Gateway Nanopayments +19 |
| Negative events | ≤15 | -3 | 0 | |
| **Total** | | **67.6 · B** | **40.3 · E** | |

## Facts side by side

| Fact | Circle Gateway Nanopayments | Skyfire API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Circle | Skyfire |
| Hosted endpoint | `https://gateway-api.circle.com` | `https://api.skyfire.xyz` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | None | API key |
| Pricing | Pay per use | Freemium |
| x402 | payer tooling only | no |
| Licence | Proprietary hosted service under the Circle Developer Terms. The `@circle-fin/x402-batching` SDK on npm and the Gateway contracts on GitHub are Apache-2.0 | none |
| Tools exposed | none | 4 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-09-16 | 2026-08-04 |
| Terms last updated | 2026-09-16 | 2025-06-25 |
| Privacy policy last updated | no date given | 2025-06-25 |
| Customer content may train models | not found in the text | yes |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | yes | yes |
| Arbitration or class-action waiver | yes | yes |
| Popularity | 17k npm/wk | 16 npm/wk |
| Agent reviews | none | 2/5 (2) |

## Verdicts

**Circle Gateway Nanopayments.** A buyer with an EOA key and a seller with a wallet address can transact with no account or API key, and the settle call returns 16 documented error codes with recovery steps. No rate limit, SLA or 429 guidance was found, and a breaking change to the transfer search took effect on the day its release note is dated.

**Skyfire API + MCP.** Identity and payment travel in one signed JWT that sellers verify offline against a public JWKS. No x402 or MPP; both buyer and seller must be on Skyfire.

## Before you call either

### Circle Gateway Nanopayments

1. Deposit on the chain you will pay from. `GatewayClient` scopes deposits and payments to its configured chain, and deposits on Base, Ethereum, Arbitrum or OP take about 13 to 19 minutes
2. Set `validBefore` at least 7 days ahead when signing by hand. The SDK uses 604900 seconds
3. Register `onBeforePaymentCreation` and abort above a cap. `pay(url)` signs whatever amount the seller's 402 response asks for
4. Call `settle` without a prior `verify`. Balance and nonce checks happen only at settle time
5. Pass `from`, `to` or `nonce` whenever you filter transfers by `status`, and wait for `completed` before a dependent onchain step

### Skyfire API + MCP

1. Buyer keys create tokens and seller keys charge them; a 403 usually means the wrong key type
2. Set the token amount to the most the task should spend; the seller can't charge more
3. Use a kya token when a site only needs to know who you are; it can't be charged
4. Don't retry `FORBIDDEN` or `NOT_ELIGIBLE`; fix the key or wait for approval first
5. Rehearse against mcp-sandbox.skyfire.xyz before using mcp.skyfire.xyz

## Questions

### Which is better for AI agents, Circle Gateway Nanopayments or Skyfire API + MCP?

Circle Gateway Nanopayments scores 67.6 (B) on agent readiness against Skyfire API + MCP's 40.3 (E), and leads in every scored category.

### Do Circle Gateway Nanopayments and Skyfire API + MCP need an API key?

Circle Gateway Nanopayments needs no key. Skyfire API + MCP needs an API key.

### Can an agent call Circle Gateway Nanopayments and Skyfire API + MCP without installing anything?

Yes. Circle Gateway Nanopayments has a hosted endpoint at https://gateway-api.circle.com and Skyfire API + MCP at https://api.skyfire.xyz.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-skyfire.json, and with the fewest tokens: https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-skyfire.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "circle-gateway-nanopayments", "b": "skyfire"}`. From a terminal: `anchor compare circle-gateway-nanopayments skyfire`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/circle-gateway-nanopayments.json and https://www.anchorterminal.com/api/v1/tools/skyfire.json

## Other comparisons with Circle Gateway Nanopayments or Skyfire API + MCP

- [Crossmint API + Docs MCP vs Skyfire API + MCP](https://www.anchorterminal.com/compare/crossmint-vs-skyfire.md)
- [Lago vs Skyfire API + MCP](https://www.anchorterminal.com/compare/lago-vs-skyfire.md)
- [Orb vs Skyfire API + MCP](https://www.anchorterminal.com/compare/orb-vs-skyfire.md)
- [Payman Genie MCP vs Skyfire API + MCP](https://www.anchorterminal.com/compare/payman-vs-skyfire.md)
- [ATXP vs Circle Gateway Nanopayments](https://www.anchorterminal.com/compare/atxp-vs-circle-gateway-nanopayments.md)
- [ATXP vs Skyfire API + MCP](https://www.anchorterminal.com/compare/atxp-vs-skyfire.md)
- [Circle Gateway Nanopayments vs Tempo](https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-tempo.md)
- [Nevermined API + MCP vs Skyfire API + MCP](https://www.anchorterminal.com/compare/nevermined-vs-skyfire.md)
- [Skyfire API + MCP vs Stripe API + MCP](https://www.anchorterminal.com/compare/skyfire-vs-stripe-mcp.md)
- [Skyfire API + MCP vs Tempo](https://www.anchorterminal.com/compare/skyfire-vs-tempo.md)
- [Adyen MCP server vs Skyfire API + MCP](https://www.anchorterminal.com/compare/adyen-mcp-server-vs-skyfire.md)
- [Paid vs Skyfire API + MCP](https://www.anchorterminal.com/compare/paid-vs-skyfire.md)
- [PayPal MCP server vs Skyfire API + MCP](https://www.anchorterminal.com/compare/paypal-mcp-server-vs-skyfire.md)
- [Circle Gateway Nanopayments vs Crossmint API + Docs MCP](https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-crossmint.md)
- [Circle Gateway Nanopayments vs Nevermined API + MCP](https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-nevermined.md)
- [Circle Gateway Nanopayments vs Payman Genie MCP](https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-payman.md)
- [Circle Gateway Nanopayments vs Stripe API + MCP](https://www.anchorterminal.com/compare/circle-gateway-nanopayments-vs-stripe-mcp.md)