SwapSpace API vs. Changelly API: a complete developer comparison

Adding swap functionality to a wallet or Web3 product affects far more than the user experience. The selected API determines how the backend requests quotes, handles expired rates, tracks transactions, and responds when a route is unavailable. It also shapes support workload when an exchange is delayed, refunded, or paused for verification.

This Changelly API vs SwapSpace API comparison examines the technical differences that matter to developers building wallets, exchanges, and other Web3 products.

The comparison uses each provider's public documentation and current B2B pages. Asset availability, request limits, commercial terms, and compliance rules can change. Confirm them through the live API and your partner agreement before launch.

What is Changelly API?

Changelly API v2 is a white-label cryptocurrency exchange API that exposes one Changelly quote and transaction service.

• Protocol: JSON-RPC 2.0 over signed POST requests.
• Authentication: X-Api-Key plus an RSA-SHA256 signature, with a partner account and public-key registration.
• Rate models: separate fixed-rate and floating-rate methods.
• Asset coverage: more than 1,000 assets on the public B2B page, with the live-enabled set returned by the API.
• Related products: separate fiat API, widget, and checkout services.

The API keeps provider selection outside the application. Fixed and floating estimates use different methods, and fixed quotes carry a short validity window. These distinctions follow the transaction into the creation step. The main implementation difference is request signing rather than route ranking.

What is SwapSpace API?

SwapSpace API v2 is a REST API that exposes offers from multiple exchange partners through one integration.

• Protocol: resource-specific REST endpoints for currencies, partners, amounts, exchange creation, and status.
• Authentication: an API key in the Authorization header, with request limits configured for each affiliate.
• Rate models: fixed and floating offers, partner filters, and a Best Amount option.
• Asset coverage: more than 3,600 assets across 675 networks and over 40 liquidity sources on the public B2B page, with live route validation required.
• Related products: an exchange widget and private transfers, with private-transfer access confirmed separately.

Each offer carries partner and route data. An application can show several offers, filter them, or use a simpler selection method. Offer IDs may be short-lived, and provider metadata can change refund-address requirements. That route-level data is the main architectural difference from Changelly's single-service contract.

Changelly API vs SwapSpace API comparison at a glance

This exchange API comparison focuses on the integration surface that a developer can verify in public documentation.

Liquidity architecture: single provider API vs aggregator

Quote selection and transparency

Changelly may source liquidity across its own infrastructure, but the partner API exposes Changelly as the service boundary. Your application requests an estimate and receives one result for the requested method and pair. This keeps the quote model compact. The product does not need to rank providers or explain why two providers returned different limits.

SwapSpace exposes liquidity aggregation directly. The amounts endpoint can return offers from all available partners or from a selected partner list. The response can include fixed and floating routes for the same pair. This gives a wallet or exchange more control over sorting. A product might rank by destination amount, estimated duration, provider policy, or its own business rules.

If an audience values provider choice or route transparency, a SwapSpace integration can display several offers and apply product-specific selection rules. A simpler product can expose one selected route. Provider identity, rate type, limits, and expected duration remain available when the interface needs them.

Availability and fallback behavior

With Changelly, if a currency is disabled or an estimate fails, the API does not expose another named provider through the same contract. The application needs a separate integration to select another route.

Before exchange creation, SwapSpace can return offers from other available partners. Once an exchange is created, the selected provider remains tied to that transaction. Changelly therefore concentrates route dependency in one service. SwapSpace exposes pre-transaction fallback within the same API.

Compliance and support boundaries

Both APIs can surface verification-related states, but responsibility is split differently. 

Changelly documents a hold status and directs the partner to route users to its security team. 

SwapSpace exposes a Verifying status, while the selected exchange provider may control the checks. Provider identity and support instructions therefore matter more in the aggregated model.

Developer experience

Access and authentication

Authentication is the clearest implementation difference and shapes the first stage of a crypto swap integration.

Changelly:

• Partner account and public-key registration.
• RSA-SHA256 signature over every JSON-RPC request body.
• Server-side integration to protect the private key.

SwapSpace:

• Affiliate account and API key in the Authorization header.
• Request limits configured for the affiliate during onboarding.
• Server-side storage for the API key.

Changelly requires more setup and signing code. SwapSpace uses a lighter credential model, while production capacity depends on the affiliate configuration.

Documentation and error handling

Changelly documentation:

• Method-level request schemas and error examples.
• Authentication samples in several programming languages.
• Migration notes and a detailed status reference.

SwapSpace documentation:

• A short REST flow from currencies and partners to exchange status.
• Validation rules for amounts, rate IDs, extra IDs, user IPs, and conditional refund addresses.

Changelly provides deeper authentication and error material. SwapSpace documents a shorter flow with more route-selection data.

Changelly's JSON-RPC responses expose method-specific codes and messages. SwapSpace's REST flow documents validation fields such as network IDs, rate IDs, extra IDs, user IPs, and conditional refund addresses. Map those upstream failures into stable internal categories before they reach the interface. Keep the original error code and exchange ID in logs so support can trace a route without showing raw provider messages to the user.

Performance and scalability considerations

Changelly publishes a default limit of 10 requests per second for relevant methods. Higher-throughput terms are not specified in the public reference.

SwapSpace does not publish a standard numeric ceiling because request limits are configured for each affiliate. Capacity planning therefore depends on the agreed partner configuration rather than a public default.

Both public flows expose polling-based status endpoints. The public references reviewed for this comparison do not define a general webhook contract, so webhook availability remains part of partner onboarding.

Polling behavior also affects capacity planning. Cache currency and partner metadata for a defined interval, avoid refreshing quotes that users cannot act on, and back off status checks after a transaction leaves its time-sensitive stages. Load tests should cover quote bursts, expired IDs, disabled pairs, and provider-side failures. Benchmark the full failure path rather than a single latency number: the product should stay responsive when routes disappear or upstream responses slow down.

Support and escalation

For a crypto exchange API for developers, support coverage matters most when a transaction stalls or enters verification. 

Changelly directs technical questions to a partner email or dedicated account manager. Its documentation describes an escalation model in which the partner provides first-line support and sends unresolved cases to Changelly's second-level team through a dedicated Slack channel.

SwapSpace provides a partner email and B2B contact form, alongside 24/7 user support. Escalation paths and response commitments depend on the partner agreement.

Before integrating either API, confirm support hours, incident notifications, status-page access, and the data required to investigate a stuck exchange.

Commercial terms and revenue model

Neither crypto exchange API charges a public integration fee. Both support partner monetization through an additional fee or revenue-sharing model.

Changelly lets API partners add a fee to the exchange rate. Its business FAQ describes 0.1% to 5% as a typical range, while the current API documentation says the fee is configured through the partner team.

SwapSpace's exchange-creation endpoint includes an optional affiliateFee parameter. The affiliate fee rate depends on the selected liquidity provider and the partner agreement.

Integration workflow

The steps below compare both crypto swap API workflows and the engineering work each crypto API integration requires.

Typical Changelly integration

1. 1. Create a Changelly partner account and generate the public and private keys.
2. 2. Register the public key with Changelly and keep the private key in a server-side secret store.
3. 3. Implement JSON-RPC 2.0 request serialization and RSA-SHA256 signing.
4. 4. Fetch the enabled currency data and map tickers, networks, memo fields, and validation rules.
5. 5. Request a floating or fixed estimate, then validate the returned amount and limits.
6. 6. Create the correct transaction type before the quote or payment window expires.
7. 7. Store the transaction ID and poll getStatus or getTransactions with backoff.
8. 8. Map every terminal, refund, expiration, and verification state to a user message and support procedure.

Changelly imposes two protocol constraints: the signature must match the exact serialized body, and v2 estimates must remain paired with v2 transaction methods.

💡 Important! Fixed and floating flows use different methods, so they should be tested separately.

Typical SwapSpace integration

1. 1. Create an affiliate account, obtain the API key, and confirm the request allowance for the target environment.
2. 2. Fetch the currency list and preserve the separate asset and network identifiers.
3. 3. Fetch the partner list and store route requirements such as refund-address rules.
4. 4. Request available amounts for the pair, amount, networks, and required rate types.
5. 5. Rank the returned offers or request the Best Amount endpoint according to the product's selection policy.
6. 6. Validate minimum and maximum values, then create the exchange before any returned rate ID expires.
7. 7. Store the SwapSpace exchange ID, selected provider, and user-facing transaction data.
8. 8. Poll the status endpoint with backoff and handle finished, failed, refunded, verifying, and expired states.

SwapSpace ties the selected offer to the created exchange. A new quote or provider produces a new exchange request.

💡 Important! If a quote expires before exchange creation, the user should approve the updated offer.

Which API fits different products?

Teams evaluating a crypto API for wallet products should first decide whether users need one exchange relationship or visible provider choice.

The table treats product fit as a starting hypothesis. Commercial terms, regions, asset demand, traffic, and internal engineering capacity can change the result.

When Changelly API makes sense

Changelly API suits products that prefer one exchange service and a compact quote response.

Its detailed signing examples and method-level error documentation help teams that value a clearly specified authentication layer. It can also suit companies that plan to evaluate Changelly's separate fiat or checkout products under the same B2B relationship.

The tradeoff is route visibility. The API returns a Changelly estimate rather than a list of named exchange providers. The integration also requires public-key registration during onboarding.

When SwapSpace API makes sense

SwapSpace is a stronger fit when provider comparison is part of the product. It exposes multiple offers, fixed and floating options, partner filters, and route metadata through one REST API. Its B2B page lists more than 40 liquidity sources and 3,600+ assets across 675 networks. The value is broader long-tail and cross-chain route coverage through one contract.

If a product retrieves multiple offers and selects a route itself, the integration may need explicit selection criteria, quote-expiry handling, and provider-specific exchange data. Products using Best Amount or a simpler flow can keep more of that routing logic outside the user interface.

Final verdict

There is no universal best swap API. 

Changelly uses JSON-RPC 2.0, RSA-SHA256 request signing, and a single-provider quote model. It offers detailed method and error documentation, but it does not expose competing provider routes through the same API. 

SwapSpace uses REST with API-key authentication and returns offers from multiple exchange partners, giving products more control over route selection and broader asset coverage.

Choose Changelly for products that prefer one provider relationship, a compact quote flow, and detailed method-level documentation. Choose SwapSpace for wallets, exchanges, and Web3 products that need provider comparison, liquidity aggregation, or wider long-tail route coverage.

Start your SwapSpace API integration

Submit the form on the SwapSpace B2B page to discuss access, request limits, and integration requirements with the product and business development teams. 

Frequently asked questions

What is the difference between SwapSpace API and Changelly API?

Changelly exposes a white-label exchange service through JSON-RPC 2.0. The application receives Changelly estimates and creates Changelly transactions. SwapSpace exposes multiple partner offers through a REST API, allowing the application to compare or filter routes before creating an exchange.

Does SwapSpace API aggregate multiple liquidity providers?

Yes. The amounts endpoint can return offers from all available partners or filter by selected partners. The public B2B page lists more than 40 liquidity sources. Availability varies by asset, network, amount, rate type, and current provider conditions.

Which API is better for crypto wallets?

It depends on the wallet's product design. Changelly fits a wallet that wants a single quote and provider relationship. SwapSpace fits a wallet that wants provider comparison, broader route coverage, or its own offer-ranking logic. Suitability also depends on coverage for the wallet's common and long-tail pairs.

Can I integrate crypto swaps without building my own exchange?

Yes. Both APIs let a product outsource exchange execution while retaining control of its interface and backend orchestration. Address validation, status handling, and support remain part of the product integration.

Does SwapSpace API support fixed and floating rates?

Yes. The amounts endpoint accepts fixed and float filters and can return both types in one request. Support depends on the partner and pair. Some offers include a short-lived rate ID that must be used during exchange creation.

How long does a typical API integration take?

Public marketing estimates are not a reliable project plan. A basic proof of concept may take days, while production timing depends on key approvals, security review, interface work, compliance states, analytics, and support tooling.

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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.