NFT APIs you can pay per call

What an NFT API does

An NFT API answers questions about non-fungible tokens or helps an application create and move them. The questions differ. Is this address an NFT contract, and which standard does it follow? Which tokens does a wallet hold right now? What metadata does a token point to? What did a collection trade for? Each answer comes from a different source: contract bytecode and interfaces, token transfer history, an off-chain metadata file or marketplace sales. An endpoint that answers one of them does not, by that fact, answer the others.

A second family of NFT APIs builds transactions. A mint builder prepares the calls that create a token; a transfer builder prepares the call that moves one. A builder returns something to sign, not a result. The token exists only after the signed transaction is submitted and confirmed on the chain, and the agent that signs it pays whatever the transaction itself transfers, on top of the fee for building it.

NFT standards matter for every one of these jobs. ERC-721 describes one token per identifier; ERC-1155 lets a contract hold several fungible and non-fungible token types and gives each identifier a balance. Other chains have their own models: on Algorand an NFT is usually a standard asset with a total supply of one, created by an application call or by an asset creation transaction. An agent that mixes these models will count, price or transfer the wrong thing.

Ownership is a state, not a fact fixed in time. A holdings answer is true at the block it was read from. Metadata can change if the contract lets its owner update the token URI, and an off-chain file can disappear. Keep the chain, the block or time and the source of every answer, so a later decision can tell whether it is still valid.

Compare the returned data and the chain

The comparison classifies each endpoint by what it returns. A contract standard check reads an address and says whether it looks like an ERC-721 or ERC-1155 contract. A holdings lookup returns the NFTs held by a wallet address. A search returns tokens or collections matching a query. A mint builder returns an unsigned transaction group. The first three return data; the last returns a transaction to sign, so it never supplies the price of a data lookup.

A route can use NFT words without being an NFT API. A route that collects a fee for a transfer the caller performs returns neither data nor a transaction, so it stays out of the comparison. A wallet balance tool that also counts NFTs answers a portfolio question, and a marketplace checkout sells a token rather than describing one. Gateways that list an NFT tool next to unrelated tools are priced on the NFT tool, never on their cheapest utility.

The chain is part of the data type. The service description names the network in these cases:

• Ethereum mainnet: OneSource.
• Algorand mainnet: fry.farm x402 Agentic Actions.

A classification on one chain says nothing about a contract with the same address on another, and a mint group for one application cannot be submitted to a different network.

Each price is the cheapest endpoint of that service for that kind of data: the same number wherever this page quotes it.

Compare 5 NFT services

Each row keeps the endpoint it is priced on. The price is the cheapest NFT data endpoint of the service or, for a service without one, its cheapest NFT endpoint. The ordering follows observed paying wallets for the whole service; it does not rank the accuracy of an answer.

$/CALL is the price of the endpoint named under it: the cheapest nft holdings of a wallet address, contract standard check: erc-721 or erc-1155 classification and nft search endpoint of the service or, for a service without one, its cheapest NFT endpoint. Never the cheapest tool of a gateway. Other kinds of data have their own price in the tables below. NFT ENDPOINTS counts the NFT endpoints out of all the endpoints the service lists. BUYERS 30D counts distinct wallets that paid the whole service on-chain in 30 days, not only its NFT endpoints. "Generalist" marks a gateway that sells more than three unrelated kinds of tools: it is never called the cheapest.

How to choose an NFT endpoint

Start from the question

Write down the question the next step needs answered. "Is this an NFT contract?" needs a standard check. "What does this wallet own?" needs a holdings lookup with the chain and the block. "Mint one token for this user" needs a builder for the right contract and a wallet that signs. Choosing the product first avoids paying for a cheap route that answers a different question.

Check the chain and the network

Confirm that the endpoint reads the chain your application uses, and whether it means mainnet or a test network. A provider that also serves a test network should say which one answered. Keep the chain identifier with every stored result.

Read what a builder asks you to sign

Before signing a built transaction, decode it. Check every transfer inside the group, its amount, asset and receiver, and the application or contract it calls. A builder fee paid over x402 and a mint payment inside the transaction are two different payments, and only the second creates the token.

Treat classifications as evidence

A standard check based on bytecode and interface calls can be wrong for proxies, unusual contracts or contracts that answer interface queries without behaving as the standard expects. Use the classification to decide what to read next, not as proof that a collection is genuine or valuable.

Test the operating limits

The monitored median uptime is 100% and the median selected quote is $0.01. Monitoring latency describes our checks, not a benchmark of your full paid workflow. Check what a retry costs and whether a failed build or an invalid address is charged.

Choose by the job

Each job below lists the services that offer its kind of output today, priced on the endpoint of that kind. A job without a candidate is left out of this list.

Check whether a contract follows an NFT standard

Use a standard check before treating a token address as a collection. Keep the classification method with the result: a best-effort introspection over RPC is evidence about the bytecode and its interfaces, not a statement about the collection, its creator or its market.

Candidates today, most buyers first: OneSource ($0.005/call, 1267 buyers) · APEX: Arc launch data and web pages for agents ($0.001/call, 21 buyers)

Build an NFT mint transaction to sign yourself

The quoted price buys the unsigned transaction group. The mint payment inside that group, the network fee and any submission are separate amounts: read the group before signing it.

Candidates today, most buyers first: fry.farm x402 Agentic Actions ($0.01/call)

What the providers describe

These paragraphs attribute products and limits to the provider that describes them. Prices follow the endpoint of the matching type, never an amount written in a description.

OneSource

OneSource is an Ethereum RPC service. Its NFT-relevant route is GET /api/chain/contract/:address, at $0.005: the endpoint description promises best-effort contract introspection through batched RPC calls, with bytecode presence, token metadata and an ERC20-like, ERC721 or ERC1155 classification. That answers one question, whether an address looks like an NFT contract, and it does so by reading the chain. The service description mentions NFTs among 25 endpoints, while the endpoint list read on October 22, 2026 had ten entries, and they did not include a route for the tokens a wallet owns, a token URI or a collection price. Treat the NFT coverage as the contract check that is actually listed. The provider says it covers Ethereum mainnet and Sepolia; record which network an answer came from.

1 NFT endpoint of 10 · $0.005/call (GET /api/chain/contract/:address) · Base · uptime 30d 100% · 224 ms · 1267 buyers in 30 days

fry.farm x402 Agentic Actions

fry.farm sells transaction builders on Algorand mainnet. POST /x402/actions/genesis-mint/mint/build, at $0.01, builds a Genesis NFT mint group: according to the endpoint description, a USDC transfer to the application followed by the mint call. The builder returns an unsigned atomic group; the agent signs it with its own wallet and submits it itself or sends it through the separate paid submit route the provider lists. The builder fee is not the price of the NFT. The USDC transfer inside the group is the mint payment, and the agent should read its amount and receiver before signing. This is a mint for one collection on one application, not a general minting service for any contract.

1 NFT endpoint of 15 · $0.01/call (POST /x402/actions/genesis-mint/mint/build) · · uptime 30d 99.4% · 247 ms · --- buyers in 30 days

Cost per call and for a larger workload

The median selected route costs $0.01 per call. At the same request shape, 100,000 calls total $1,000.00. Use the generated table as a reference calculation, then count how many calls one finished task needs.

Each service at the price of its main NFT endpoint, the one named in the table above.

A finished NFT task often needs more than one call. Checking a contract, reading the holdings of a wallet and fetching metadata are separate requests, and a mint needs a build, a signature and a submission. The network fee of a submitted transaction and any payment inside it are not part of the x402 price. Keep the endpoint, the parameters, the quote and the outcome of each call, so that a cheap first step is not mistaken for a cheap finished task.

Inspect a request and its payment evidence

For a standard check, OneSource documents GET /api/chain/contract/:address, with a reference quote of $0.005. Replace the path parameter with the contract address and read the classification together with the bytecode presence and the metadata fields the response returns.

The listed method and description establish the advertised contract. This explanation does not reproduce an HTTP 402 challenge or certify a paid response. Open the service page for its payment evidence and obtain the challenge for the exact request before authorizing payment. Compare resource, method, network, asset and amount together, and do not reuse a challenge for a neighboring RPC tool.

How this comparison is built

The comparison starts with services that are online and payment-ready, have a known price, a description of at least 80 characters and measured 30-day uptime of at least 90%. Task selection then reads the documented endpoints: a service enters when it lists a priced endpoint that returns NFT data or builds an NFT transaction. A mention of NFTs in a service description is not enough. Pages below the index threshold can still be read directly.

Provider claims were reviewed against the public service and endpoint descriptions captured on October 22, 2026. They remain provider claims. Monitoring supplies operating figures and reference prices; it does not establish that a classification is correct or that a built transaction does what its description says. Buyer counts describe observed paying wallets for the whole service, with the coverage limits explained on its linked page.

Questions

How to pay

Each service answers an unpaid call with HTTP 402 and its price; your agent signs a USDC payment on the listed network and retries. No API key, no account, no subscription. See what x402 is.

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