Errors

Every failure is a JSON object carrying a machine-readable error code, which never changes meaning, and a message written for people. Branch on the code; log or display the message.

{ "error": "insufficient_balance", "message": "wallet holds 0 tokens" }

Your request

Code	HTTP	Meaning
invalid_request	400	Something required is absent, or a field has the wrong shape.
invalid_address	400	An address field (token, from, beneficiary, …) does not parse as one.
invalid_amount	400	amount is zero, negative or not numeric, or a percentage was given on a buy. four.meme also rejects token amounts that are not whole gwei; the API rounds sells down for you.
invalid_action	400	Only "buy" and "sell" are accepted.
token_not_found	404	The address is neither a Flap nor a four.meme token on BNB Chain. Check you copied the token, not a pool.

Trading

Code	HTTP	Meaning
insufficient_funds	400	Not enough BNB in from for the trade plus gas. The message states the balance and the requirement side by side. It has to be BNB on BNB Chain - a balance of USD1 or another asset does not pay for gas.
insufficient_balance	400	Selling more tokens than the wallet holds, or paying with a quote asset you don't hold enough of. "100%" sells everything.
slippage_exceeded	400	Between quoting and building, the price moved past what slippage allows. Re-request; on a volatile token, allow more.
quote_asset_required	400	The token is priced in an asset the launchpad cannot swap BNB into (or out of), or a graduated four.meme token's quote asset has no PancakeSwap V2 pool from BNB. Hold the asset and buy with payWithQuote: true; sells pay out in the asset.
unsupported_version	400	A four.meme token from its V1 manager (created before September 2024), still on its curve. Readable, not tradeable here; it trades normally once graduated.
buy_quota_exhausted	400	The token caps curve buys per wallet and this wallet has used its cap.
amount_too_small	400	So little that the trade would return nothing. Increase amount.
not_tradable	409	The token is not in a tradeable state right now (mid-migration to PancakeSwap, or blocked by the launchpad). Retry in a minute.
insufficient_allowance	400	The spender lacks an allowance the trade relies on. Request again and an approve transaction is prepended.

Sending

Code	HTTP	Meaning
not_ours	400	/api/send only broadcasts transactions this API built: Flap and four.meme trades, launches, approvals to our routers or the launchpads' contracts, and claims. Anything else is refused before it reaches the chain.
wrong_chain	400	The signed transaction is for another chain id; this API relays BNB Chain (56).

Creating a token

Code	HTTP	Meaning
invalid_pair_token	400	pairToken is not an address and not one of the known tickers (listed in the message).
pair_token_not_approved	400	Flap doesn't accept that asset as a quote. Use BNB or one of the enabled assets.
invalid_tax	400	buyTaxBps / sellTaxBps is above 10000.
invalid_logo	400	logo is not a fetchable image URL or a valid base64 data: URL.
launch_rate_limited	400	Flap limits how often one wallet may launch. Wait and retry.
launcher_blocked	400	Flap has blocked from from launching.
metadata_already_used	400	Another token already uses this metadata CID. Pin fresh metadata.
name_blacklisted	400	Flap rejects this name or symbol.
flap_disabled	400	Flap has paused launching or trading. Try later.
missing_file	400	The multipart upload contained no file part.
not_an_image	400	The file's content type is not image/*.
file_too_large	400	Images are capped at 5 MB.
invalid_upload	400	The multipart body could not be parsed.

Creator revenue

Code	HTTP	Meaning
nothing_to_claim	400	No tax, LP fees or dividend is pending for this wallet on this token. The message notes how much Flap has already paid out on its own.
not_beneficiary	400	Only the token's beneficiary can claim its LP fee share.
not_graduated	400	LP fees exist only once the token has graduated to PancakeSwap.

Limits

Code	HTTP	Meaning
rate_limited	429	Over 3 calls a second to a single endpoint from one IP. Retry-After: 1 says when to try again.
too_many_connections	429	One launch-feed socket per IP is the cap; this would have been the second.

Everything else

Code	HTTP	Meaning
revert	400	Simulation shows the transaction failing for a reason without its own code; message carries the decoded contract error.
rpc_error	502	BNB Chain (or Flap's IPFS gateway) could not be reached. Retry.

Passing every check here does not guarantee a landed trade: the price can still move past minOut before your transaction is mined, in which case it reverts and only gas is spent.