GET /v0/ramp/quotes, POST /v0/ramp/sessions) speak Sumvin’s domain primitives: from_asset, to_asset, and chain_id. Direction (buy or sell) is inferred from which side is fiat. Provider-specific token codes are translated internally — your integration only ever sees Sumvin asset symbols.
Direction inference
You always send the same triplet —from_asset, to_asset, chain_id. Sumvin reads the fiat-vs-crypto sides and infers the direction.
chain_id always describes the crypto leg — the network the crypto asset lives on. Whether you are buying or selling, chain_id is the chain you are settling crypto on or debiting from.
Assets
from_asset and to_asset accept Sumvin asset symbols. Discover the full set programmatically:
Fiat
Any value in theFiatSymbol enum is accepted as the fiat side of a pair. Whether a given fiat code returns live quotes depends on the country and the service providers that serve it.
Crypto — rampable today
Each crypto asset is identified by the pair(symbol, chain_id). The table below lists the assets currently eligible for fiat ramp. A pair outside this set returns 400 Asset Not Supported for Ramp (RAMP_UNSUPPORTED_ASSET).
Sei mainnet (chain_id: 1329) is the first launch chain. Base (chain_id: 8453) is also supported.
Sei — chain_id: 1329
Base — chain_id: 8453
Other chains (Ethereum mainnet, Optimism, Polygon, Arbitrum, Avalanche, BNB Smart Chain) appear in the
SupportedChains enum and are returned by GET /v0/assets as catalog entries — but they are not currently rampable. Quote and session calls against those chains return 400 Asset Not Supported for Ramp. Coverage expands as service providers extend their support.Crypto — catalog only (not yet rampable)
These assets are present in the Sumvin catalog (visible onGET /v0/assets, holdable in a Sumvin wallet) but cannot currently be bought or sold through the ramp endpoints. Quote calls return RAMP_UNSUPPORTED_ASSET.
Sei — chain_id: 1329
Base — chain_id: 8453
WETH on Base is not separately rampable — buying or selling Ether on Base uses ETH as the symbol. The wrapped variant exists in the catalog for balance accounting and DeFi interactions.Country codes
country_code is an ISO 3166-1 alpha-2 value drawn from the SupportedCountry enum. It filters quotes to providers live in that market. Defaults to US. Values outside the enum are rejected at the API boundary with 422 Unprocessable Entity before the request reaches the provider.
Americas
Europe
APAC
MENA + Africa
A format-valid country can still return an empty
quotes array if no service provider offers that pair in that market — treat GET /v0/ramp/quotes as the source of truth for live coverage.
Payment method types
payment_method_type is an enum drawn from MeldPaymentMethod. Values outside the enum are rejected at the API boundary with 422 Unprocessable Entity.
The provider distinguishes broad types (categories) from subtypes (specific rails). Both are accepted in the same field. Pass a type to receive quotes across all of its subtypes; pass a subtype to narrow to that single rail. Omit the field to let the provider rank the full set.
Types
Subtypes
Direction guidance
- Buys —
CREDIT_DEBIT_CARD,APPLE_PAY,GOOGLE_PAY,ACH,SEPA,BANK_TRANSFERare most commonly available. - Sells / off-ramp —
ACH,SEPA,BANK_TRANSFER,LOCAL_BANK_TRANSFER. Card rails generally do not support payouts.
Error reference
Errors follow RFC 7807 Problem Details with a Sumvinerror_code field.
Validation behaviour
- Enum / type failure (e.g. unknown country code, invalid payment method) →
422 Unprocessable Entitywith the offending field in the validation detail. The request is rejected at the API boundary and never reaches the provider. - Pair shape failure (both fiat, both crypto, missing crypto leg) →
400 Invalid Asset Pair. - Crypto pair not in catalog →
400 Unknown Asset. - Crypto pair in catalog but no provider coverage →
400 Asset Not Supported for Ramp. - All inputs valid but no provider serves the pair for the country →
200 OKwith an emptyquotesarray onGET /v0/ramp/quotes. Re-quote with a different combination. - Upstream provider rejects →
502 Ramp Provider Error.
Related
- Buy and sell — direction model
- On-ramp quickstart — end-to-end flow
- Reference — status and error codes