Pairs & Marks API

Which pairs does CRX list?

Every supported pair, with its live Pyth (Hermes) feed id. Most are USD-base USD/XXX feeds; the four FX majors (EUR/USD, GBP/USD, AUD/USD, NZD/USD) are listed in their native XXX/USD orientation. Two pairs, USDT/USD and USDC/USD, are not FX at all. They are crypto/stablecoin pairs priced off the Pyth Crypto.USDT/USD and Crypto.USDC/USD feeds, and they are the only pairs that trade 24/7 with no session gate. All settle in USDC. None deliver currency.

27 listed pairs - all but two are FX; USDT/USD and USDC/USD are 24/7 crypto/stablecoin pairs. Every one settles in USDC against a live Pyth fixing - none deliver currency.
Pair
Quote currency
Live Pyth feed
AUD/USD
Dollars
0x67a6f93030…22854a80
EUR/USD
Dollars
0xa995d00bb3…e81ec30b
GBP/USD
Dollars
0x84c2dde963…3df0a7c1
NZD/USD
Dollars
0x92eea8ba1b…bfafa4c7
USD/BRL
Reais
0xd2db4dbf1a…d7a95906
USD/CAD
Canadian dollars
0x3112b03a41…eaa2ecca
USD/CHF
Francs
0x0b1e3297e6…a63e28f8
USD/CLP
Chilean pesos
0xd407a4b25c…cc3e84c7
USD/CNH
Yuan
0xeef52e09c8…2e332e66
USD/COP
Colombian pesos
0xcaffb53eda…ef4edf8d
USD/HKD
Hong Kong dollars
0x19d75fde7f…b23aff4c
USD/IDR
Rupiah
0x6693afcd49…b9207433
USD/INR
Rupees
0x0ac0f9a288…4fcf1809
USD/JPY
Yen
0xef2c98c804…3042fd52
USD/KRW
Won
0xe539120487…201be7e3
USD/MXN
Mexican pesos
0xe13b1c1ffb…866b77ca
USD/NOK
Kroner
0x235ddea9f4…596023a3
USD/PEN
Soles
0x5a90fd5841…b192446a
USD/PHP
Pesos
0x2bda7f268b…9e0a68c9
USD/SEK
Kronor
0x8ccb376aa8…e43fc676
USD/SGD
Singapore dollars
0x396a969a9c…8bdb4918
TESTUSD/TEST
TEST
0x0…0x0
USD/TRY
Lira
0x032a2eba1c…8744e058
USD/TWD
Taiwan dollars
0x489f02f2f1…fcd5a8e0
USD/ZAR
Rand
0x389d889017…97f493f1
$USDC/USD
Dollars
0xeaa020c61c…a9e9c94a
₮USDT/USD
Dollars
0x2b89b9dc8f…88e2e53b

Where does the pair set come from?

One config file: config/pairs.json. It is the single source of truth read by the frontend selector, the maker bot, the TWAP keeper, and the on-chain seeding script. Each entry carries:

Field	Meaning
symbol	The pair label, e.g. USD/INR. pairId = keccak256(symbol) on-chain.
base / quote	The two legs. Most pairs are USD-base (USD/INR); the four FX majors are listed in their native XXX/USD orientation (EUR/USD, GBP/USD, AUD/USD, NZD/USD).
feedId	The Pyth (Hermes) price feed id for the pair.
schedule	The market-hours string driving the open/closed session gate.
inverted	Always false. Each pair is read in the orientation Pyth publishes it, never a reciprocal.

How do I read the session for a pair?

From the schedule string in config/pairs.json. Its shape:

America/New_York;<Mon>,<Tue>,<Wed>,<Thu>,<Fri>,<Sat>,<Sun>;<holiday overrides>

• The first field is the venue timezone.
• Then seven per-weekday windows, HHMM-HHMM. O = open all day, C = closed. & joins two windows in one day.
• Then holiday overrides, MMDD/<window-or-C>.

The gate shows a pair Open in-session and Closed out-of-session.

NoteTwo pairs are always open. USDT/USD and USDC/USD each carry a seven-day schedule (O,O,O,O,O,O,O): the crypto/stablecoin pairs, priced off the Pyth Crypto.USDT/USD and Crypto.USDC/USD feeds, never close. Every other pair is FX and follows a weekday or session window. Read the schedule string per pair rather than assuming an FX week.

NoteSome LatAm pairs only publish live during their local bank session. USD/CLP, USD/COP, and USD/PEN are Open in-session and Closed out-of-session, not dead, just session-windowed. The freshness overlay halts trading if an in-session feed stalls.

How do I read the live mark?

Three distinct prices; do not confuse them.

Price	Source	Endpoint / read	Binding?
Indicative spot	Pyth Hermes	GET <hermes>/... direct (see below)	no
On-chain mark	per-pair FX oracle	on-chain _markRate, read over RPC	margin only
Fixing	FX oracle, on/after delivery date	on-chain, at settlement	yes

• Indicative spot comes straight from Pyth Hermes, base https://hermes.pyth.network (the hermes field in config/pairs.json), keyed by feedId. It refreshes every few seconds and is not firm.
• On-chain mark is what the contract marks margin against. Read it over RPC from the per-pair FX oracle; it is fixed to expo = −8.
• Fixing is the single rate that settles the trade, read once at the delivery date.

The full distinction: Oracle & Rate Sources (~3 min).

NoteThe relayer does not serve a live-mark endpoint. The indicative spot is read from Pyth Hermes directly; the on-chain mark and fixing are read on-chain over RPC. There is no relayer GET /mark.

Which relayer endpoint relates to pairs?

One: GET /margin, the vol-scaled initial-margin schedule for a pair. It is keyed by the on-chain pairId (keccak256(symbol)), not a label, and returns the full schedule. The exact parameters and response shape live with the endpoint reference.

CRX API: GET /margin · ~4 minMargin schedule params (pairId, notional) and the full response shape

Pair labels passed to /rfq and on-chain calls must match a symbol in config/pairs.json exactly.