Errors

An invalid request returns 400 Bad Request, and a request over the rate limit 429 Too Many Requests. Both come with a plain text (text/plain) message, not JSON. Show the text to developers, not end users: it’s meant for debugging.

“No route found” is not an error: it’s 200 OK with an empty array.

/route/outcome has messages of its own.

Messages

Message	Cause
Failed to deserialize query string: missing field `token_in`	A required parameter is missing, probably DEX Aggregator’s fault
Failed to deserialize query string: no variant of enum Amount found in flattened data	Neither amount_in nor amount_out is given
Failed to deserialize query string: ...	A parameter has the wrong format, for example an invalid token ID or account ID
Failed to deserialize query string: dexes: Empty dex id	Empty ID in dexes, like dexes= or dexes=Rhea,
Failed to deserialize query string: fees: Invalid referral fees: ...	fees isn’t a JSON object of account IDs to numbers
Failed to deserialize query string: fees: Referral fee of alice.near must be between 0 and 0.05	A fee is negative or over 5%
Failed to deserialize query string: fees: Referral fee of alice.near must be a whole number of millionths	A fee has more than 6 decimal places
Failed to deserialize query string: fees: At most 4 accounts can be paid	More than 4 accounts in fees
Failed to deserialize query string: fees: Referral fees must add up to at most 0.05	The fees add up to more than 5%
Amount must be greater than 0	amount_in or amount_out is 0
Token in and token out must be different	token_in equals token_out
Slippage must be between 0.00 and 1.00	Fixed slippage out of range
Min slippage must be between 0.00 and 1.00	Auto min_slippage out of range
Max slippage must be between 0.00 and 1.00	Auto max_slippage out of range
Max slippage must be greater than min slippage	max_slippage < min_slippage
Invalid dex id: Foo	Unknown ID in dexes. IDs are case-sensitive. IDs of removed DEXs are accepted and give no quotes

Over the WebSocket, the same messages come as { "id": ..., "error": "..." }, except that parsing errors lose the Failed to deserialize query string: and <parameter>: prefixes: Failed to deserialize query string: dexes: Empty dex id comes as Empty dex id.

Rate limits

Requests without an API key in key are rate limited per IP address (per /64 for IPv6). Over the limit, GET /route and GET /route/outcome return 429 Too Many Requests with a Retry-After header in seconds and the text Rate limit exceeded, retry in <n>s or use an API key.

On the WebSocket, the connection request counts, and so does every message with a query. Over the limit, the connection fails, or the message gets { "id": ..., "error": "Rate limit exceeded, retry in <n>s or use an API key" }.

A wrong key gets 401 Unauthorized with Invalid API key, and on the WebSocket the connection fails.