Best crypto swap APIs for Web3 wallet developers

A wallet swap screen looks simple. The work behind it is not. A provider must return a usable quote, build the right transaction or deposit flow, handle network-specific details, and expose enough status data for support when a transfer stalls. A poor integration pushes that complexity onto the user through unclear fees, failed approvals, missing memos, or a refund process nobody can explain.

This guide compares five products that solve different parts of the problem: Changelly, SwapSpace, ChangeNOW, 1inch, and LI.FI. Some operate a hosted exchange flow. Others route onchain liquidity or cross-chain bridges. The best choice depends on what your wallet can sign, which chains matter, and how much of the execution stack your team intends to own. For a wallet team, a crypto swap API is infrastructure for a user journey, not a logo added to a feature page.

Quick answer: Use a hosted exchange API, such as Changelly API or ChangeNOW Exchange API, when your wallet needs a deposit-and-payout flow or support for assets beyond its onchain stack. Use an onchain router, such as 1inch Swap API or LI.FI API, when your wallet can own approvals, signing, gas, and transaction recovery. For provider comparison across hosted exchange routes, use an exchange aggregation API such as SwapSpace API.

Swap API comparison table

Coverage in this table reflects provider pages checked in September 2026.

What a crypto swap API does inside a wallet

Crypto swap APIs fall into two main categories.

• Hosted swap APIs: In a hosted model, the API commonly returns a deposit address, expected amount, payout address, quote, and order status. The wallet asks the user to send funds, then follows the provider's status until the payout arrives. The provider handles the exchange and settlement path outside the wallet interface.
• Onchain swap APIs: The wallet receives transaction data, requests an approval when needed, asks the user to sign, broadcasts the transaction, and monitors it. A cross-chain route may contain more than one transaction or a bridge wait state. That shifts product design and support work to the wallet. A crypto exchange API can remove custody from the wallet's backend, but it does not remove the need to explain what happens after the user clicks Confirm.

For Web3 wallet development, the integration should also handle token decimals, chain IDs, native-gas balances, address formats, destination tags, minimum amounts, expired quotes, and provider-specific KYC or AML states. The most useful crypto wallet API is the one whose error and status model your product can present without inventing vague messages.

How we compared the swap APIs

The comparison looks at functionality, asset and network coverage, integration path, documentation, liquidity model, rate types, fees, limits, and B2B fit. It also checks the pieces that often surface after launch: fixed-rate availability, memo handling, refund instructions, transaction-status updates, webhooks or polling, and the point at which a provider can request verification. SwapSpace appears here as one of the compared products, not as the reference point for every wallet.

No single best crypto exchange API fits every wallet. A crypto API for developers needs clear execution, state, and recovery information. Treat crypto API integration as product work, not a connector task. A DEX aggregator API and an exchange aggregator API are different products.

Sources and check date: official B2B pages and technical documentation reviewed on September 10, 2026. Coverage and route availability can change without notice.

The 5 best swap APIs for Web3 wallets

These five APIs cover two main approaches. Changelly, SwapSpace, and ChangeNOW provide hosted exchange flows. 1inch and LI.FI provide onchain routing, with LI.FI also covering cross-chain execution. The table is a starting point. The sections below explain the trade-offs a wallet team will feel during implementation.

1. Changelly Crypto Exchange API

Changelly API is a hosted crypto exchange API for wallets that want a white-label swap flow. Its API v2 documentation covers quote estimation, transaction creation, fixed-rate transactions, and status retrieval.

API functionality: The API returns rate and limit estimates before a wallet creates a standard or fixed-rate transaction. API v2 uses JSON-RPC, and the provider requires backend-side integration because the API key must not be exposed in a client app.

Assets and networks: The available currency set is provider-managed. Build the wallet’s selector from live availability and validation responses instead of hard-coding a coin list.

Integration and docs: The documentation specifies API keys and RSA-SHA256 request signing. That makes the backend boundary explicit, which suits wallets with a server component but adds work for a fully client-side product.

Fees and monetization: Partners can request an API extra fee. The documentation gives 0.5% as an example, while the commercial setting is arranged with Changelly.

Swap flow: A wallet estimates the exchange, collects the destination address, creates a transaction, displays the deposit instructions, and polls the transaction status until completion or a support state.

Best suited for: Wallets that need a hosted cryptocurrency exchange API, want fixed-rate transactions, and can keep credentials and signing logic on a backend.

Limitations: The provider owns the exchange process after deposit. Your UI still needs clear quote-expiry, minimum-amount, status, and verification messaging.

2. SwapSpace API

SwapSpace API is a crypto exchange aggregation API for wallets that want to compare exchange offers from multiple liquidity providers through one integration. Its B2B page currently lists 3,600+ assets across 675 networks and 40+ liquidity sources, including centralized, decentralized, and off-chain providers.

API functionality: The wallet can request offers, let the user compare them, create an order, and follow the order state. The provider describes API-key and exchange-widget entry points, so teams can choose between a more native flow and a faster embed.

Assets and networks: Coverage includes chains that onchain-only stacks often omit, such as native Bitcoin, Tron, and Monero. Pair availability still depends on the selected provider and the amount.

Integration and docs: The REST documentation covers the order flow. Provider details, KYC or AML policy indicators, and speed data are useful inputs for a wallet’s offer screen and support tooling.

Fees and monetization: The B2B product offers revenue sharing. Confirm the applicable split, payout process, and any pair-level limits during partner onboarding rather than displaying a generic margin claim in the wallet.

Swap flow: The user chooses an offer, receives deposit and payout details, sends the source asset, then sees status changes through settlement. A wallet should preserve the order ID, amount, addresses, and any memo in its activity record.

Best suited for: Wallets that need a crypto swap API integration with broad multi-chain coverage, provider comparison, and access to hosted exchange routes, including native assets that may be difficult to support through DEX-only infrastructure.

Limitations: An aggregated quote is not a guarantee that every provider will accept every deposit. The integration needs quote expiry, network checks, and a visible route to refund guidance.

3. ChangeNOW Exchange API

ChangeNOW Exchange API is a hosted crypto exchange API for wallets, payment products, and exchange interfaces. Its current API page lists 1,500+ assets and more than 2.25 million exchange pairs, with standard and fixed-rate flows.

API functionality: The product covers quote generation, transaction creation, currency availability, and transaction status. It also presents a private-transfer feature, but treat it as a separate product capability and validate its exact chain coverage before exposing it in a wallet.

Assets and networks: ChangeNOW states that it combines CEX and DEX liquidity and supports 75+ networks for private transfers. Use its available-currencies endpoint to decide what the wallet can show at a given moment.

Integration and docs: The ChangeNOW API documentation is published as a Postman collection, with an API key issued through the partner account. Its status page and currency-status endpoint matter for operational monitoring.

Fees and monetization: The provider states that there are no setup or monthly fees and that partner referral terms start from 0.4%. The exact percentage and eligible pairs need to be confirmed in the partner agreement.

Swap flow: The standard flow follows market conditions. A fixed-rate flow has separate availability and configuration. In either case, surface the source amount, output estimate or guarantee, deposit deadline, and destination details before the user sends funds.

Best suited for: Wallets that want a hosted crypto exchange API integration, optional fiat on- and off-ramps, and partner-managed exchange support.

Limitations: Fiat ramps are available on request, so they should not be treated as an automatic part of the base API. Hosted flows also need provider-policy and transaction-status handling in the product layer.

4. 1inch Swap API

1inch Swap API is an onchain DEX aggregation API for wallets that can own approvals, signing, and execution. Its current documentation describes Classic, Intent, and Cross-Chain modes, each with a different signing and execution path.

API functionality: Classic mode returns quote and transaction data for a wallet to sign and broadcast. Intent mode can use gasless execution. Cross-chain mode adds a cross-chain execution path. 1inch API offers a free API plan suitable for prototyping and initial integration testing.

Assets and networks: The documentation lists 15+ supported networks, primarily EVM networks plus Solana, and separates coverage by execution mode. Token availability comes from the network and liquidity sources, so the selector should be driven by supported-chain and quote responses.

Integration and docs: The API uses a key in the Authorization header. Official TypeScript SDKs and mode-specific examples help with implementation, but the wallet still owns approvals, transaction signing, gas estimation, and broadcast UX.

Fees and monetization: Classic mode supports an integrator fee parameter. The documentation shows a 0 to 3 range, but a team should confirm its commercial and user-experience implications before setting a fee.

Swap flow: A typical Classic flow is quote, approval when required, signed swap transaction, broadcast, and confirmation tracking. Handle allowance state and native-token gas up front. They are common reasons for a swap to fail before execution.

Best suited for: EVM-focused wallets that want direct onchain execution, are comfortable owning transaction UX, and need a DEX aggregator API rather than a deposit-and-payout exchange flow.

Limitations: It does not replace a provider that supports every non-EVM asset or manages offchain settlement. The integration also puts more gas, approval, and transaction-replacement responsibility on the wallet.

5. LI.FI API and SDK

LI.FI API is a cross-chain routing API for multi-VM wallets that need onchain and cross-chain execution. It combines a REST API, JavaScript and TypeScript SDK, and embeddable widget. Its current documentation states coverage across 58 blockchains, including EVM networks, Solana, Bitcoin, and Sui.

API functionality: The LI.FI API returns quotes and routes. The SDK can execute routes, manage transaction steps, and emit events. Its status model includes completed, failed, partial, and refunded transfers, which gives a wallet more precise language for cross-chain support cases.

Assets and networks: LI.FI aggregates supported bridges, exchanges, and solvers. It has SDK providers for EVM, Solana, UTXO, and Sui. Coverage is route-dependent, so query the supported-chain and token endpoints instead of relying on a static list.

Integration and docs: Teams can create an integration and obtain an API key through the LI.FI Partner Portal. Production limits and commercial arrangements depend on the integration plan. An API key increases limits and must stay on the backend. The widget does not require a frontend key. The SDK offers a middle path for wallets that want control without implementing every route step themselves.

Fees and monetization: Integrators can configure their own fee through the fee parameter and manage fee recipients through the Partner Portal. Fee collection and withdrawal mechanics vary by chain. The provider documents direct fee forwarding on EVM, Solana, Sui, and Bitcoin, subject to the route rules.

Swap flow: A route may require token approval, source-chain signing, bridge processing, and destination delivery. Present each stage as a real step. Do not reduce a multi-transaction route to a single spinner with no recovery information.

Best suited for: Multi-VM wallets that need swap and bridge routing, route events, and a choice between REST, SDK, and crypto swap widget integration.

Limitations: Cross-chain execution has more moving parts than a same-chain swap. Quote expiry, bridge fees, slippage, destination-chain delivery, and refund states need product decisions before launch.

How to choose a swap API for your wallet

• Start with the wallet architecture. A non-custodial client-only wallet can integrate an onchain route directly, but it should not embed server credentials. A wallet with a backend can use hosted exchange APIs and server-side signing schemes. That boundary decides which providers are technically viable.
• Test the routes your users will use: a same-chain token swap, an EVM-to-EVM route, a Bitcoin or other UTXO path where relevant, a memo-required asset, a minimum-amount failure, an expired quote, and a failed or refunded transaction. Production-like edge cases matter more than a successful demo route.
• Ask each provider for the operational contract: rate limits, quote validity, fixed-rate conditions, webhook availability, polling guidance, status vocabulary, support channel, KYC triggers, refund ownership, and service-level commitments. The provider's states should map cleanly to your activity feed and support playbook.
• Apply the same checks to 0x, Jupiter, SimpleSwap, and Rango: execution model, supported chains, rate control, recovery handling, and commercial terms.

Security checklist for integrating a crypto swap API

• Keep API keys and request-signing material on a backend or another server-side environment. Never ship them in a mobile app or browser bundle.
• Validate destination addresses, tags, chain IDs, token contracts, and minimum amounts before the user confirms.
• Treat quotes as expirable. Re-check amounts, rate type, network, and route conditions before creating the transaction or deposit flow.
• Persist quote, order, and transaction IDs with the status history, and define who owns refunds, retries, and support at each failure state.
• Test KYC or AML holds, failed deposits, approvals, insufficient gas, expired quotes, and bridge or refund states before launch.

Conclusion

The right swap API depends on the chains your wallet supports, the flow users can understand, and the commercial model you can explain clearly. Hosted APIs reduce the amount of execution infrastructure your team owns. Onchain aggregators give the wallet more control and more responsibility for signing, approvals, and transaction states.

For a provider-comparison and hosted exchange approach, review the SwapSpace B2B page and its API documentation before deciding how to fit the flow into your wallet.

FAQ

What is a crypto swap API?

A crypto swap API gives a wallet the data and instructions needed to exchange one crypto asset for another. Depending on the provider, it can return a hosted deposit-and-payout flow or transaction data for an onchain swap.

What is the difference between a swap API and a DEX aggregator API?

A swap API is a broad term. It can describe a hosted exchange, an exchange aggregator, or an onchain router. A DEX aggregator API usually finds and executes onchain liquidity across decentralized exchanges, while a hosted provider can manage the exchange after a user deposits funds.

What is the difference between a crypto swap API and a bridge API?

A crypto swap API exchanges one asset for another, while a bridge API primarily moves assets or value between blockchains. Some cross-chain swap APIs combine both operations into one route, so the user can send one asset on one chain and receive another asset on another chain.

Are swap APIs non-custodial?

The label depends on the flow. An onchain route can keep signing in the wallet. A hosted exchange flow may be non-custodial from the wallet provider’s perspective, yet the user still sends funds to a provider-controlled deposit address for execution. Explain the exact path.

Do swap APIs require KYC?

Verification requirements are set by each provider and depend on jurisdiction and transaction. The wallet should surface the provider’s policy to the user before funds are sent and show the status if verification is requested.

How do wallet developers make money from swap integrations?

Commercial models include revenue share and an integrator fee configured on each transaction or route. Show the user any fee that affects the final amount, then confirm payout and reporting terms with the provider.

How long does it take to integrate a swap API into a wallet?

A basic quote and transaction flow can be built quickly with a mature API. A production integration takes longer because it needs asset validation, status handling, analytics, support playbooks, security review, and testing of unsuccessful routes.

Which swap API supports the most blockchains?

Published counts change often and measure different things. On the sources checked for this article, SwapSpace lists 675 networks, while LI.FI documents 58 blockchains. Compare the chains and pairs your wallet needs instead of treating one headline number as a universal answer.

Is there a free swap API for testing?

1inch documents a free prototyping plan for initial responses. LI.FI allows API use without a key at base rate limits. Other providers use partner onboarding or commercial terms, so verify the current entry conditions before planning a test environment.

Can a wallet integrate multiple swap APIs?

Yes. A wallet can integrate multiple swap APIs, then use a routing layer to decide which service appears for a given asset, network, amount, or user region. That adds work: normalize quotes, fee disclosures, status vocabularies, KYC states, refund paths, and support ownership. An aggregation API such as SwapSpace can reduce the number of partner integrations for hosted exchange routes, while 1inch and LI.FI cover a different, onchain execution model.

Do crypto swap APIs support Bitcoin?

Support depends on the model. An API focused mainly on EVM networks, such as 1inch, does not serve native Bitcoin in the same way as a hosted exchange aggregator. SwapSpace can offer native Bitcoin routes through its providers. LI.FI lists Bitcoin among its supported blockchains, but route availability still depends on the asset, route, and wallet setup. Check the live quote or availability endpoint before showing a Bitcoin pair.

This comparison is for informational purposes. API functions, asset coverage, limits, fees, and compliance requirements may change. Review current documentation and contractual terms before deploying a production cryptocurrency exchange API.