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Base URL: http://data.graylayer.tech All data endpoints require an x-api-key header. Timestamps are UTC RFC 3339 (e.g. 2026-03-26T12:00:00Z). Results are always sorted ts ascending; limit truncates after sort.

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GET /health

curl http://data.graylayer.tech/health

{"status": "ok"}

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GET /api/:exchange/tickers

List all tickers collected for an exchange. Use prefix to narrow results — useful when you know the series you want (e.g. KXBTC15M) but not every individual contract.
ParamInTypeDescription
exchangepathstringkalshi, gemini, or polymarket_us
prefixquerystringCase-insensitive prefix filter (optional)
curl -H "x-api-key: your_key" \
  http://data.graylayer.tech/api/kalshi/tickers
Response 
{
  "exchange": "kalshi",
  "count": 3,
  "tickers": [
    "KXBTC15M-26MAR281500-50",
    "KXBTC15M-26MAR281515-52",
    "KXBTC15M-26MAR281530-54"
  ]
}
Tickers are sorted alphabetically. If your key has ticker_prefixes, only matching tickers are returned regardless of what prefix you pass.

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GET /api/:exchange/snapshots/:ticker

Get snapshot rows — full orderbook state at discrete points in time. Each row represents the complete book at that moment (not a delta). Multiple rows at the same ts represent different price levels.
ParamInTypeDescription
exchangepathstringExchange name
tickerpathstringTicker symbol
start_tsqueryRFC 3339Rows at or after this time (optional)
end_tsqueryRFC 3339Rows at or before this time (optional)
limitqueryintegerMax rows returned, applied after sort (optional)
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/kalshi/snapshots/KXBTC15M-26MAR281500-50?limit=100"
Response 
{
  "exchange": "kalshi",
  "ticker": "KXBTC15M-26MAR281500-50",
  "count": 4,
  "rows": [
    {"ts": "2026-03-26T14:00:01.193Z", "side": "bid", "price": "0.4800", "quantity": "150.00"},
    {"ts": "2026-03-26T14:00:01.193Z", "side": "bid", "price": "0.4700", "quantity": "300.00"},
    {"ts": "2026-03-26T14:00:01.193Z", "side": "ask", "price": "0.5200", "quantity": "80.00"},
    {"ts": "2026-03-26T14:00:01.193Z", "side": "ask", "price": "0.5300", "quantity": "200.00"}
  ]
}
start_ts is clamped to your key’s max_data_age_days window. Anonymous access is always clamped to the last 1 day.

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GET /api/:exchange/deltas/:ticker

Get delta rows — incremental changes to the orderbook. A positive quantity_delta means a level was added or increased; negative means it was reduced or removed. Reconstruct the full book by applying deltas to a snapshot.
ParamInTypeDescription
exchangepathstringExchange name
tickerpathstringTicker symbol
start_tsqueryRFC 3339Rows at or after this time (optional)
end_tsqueryRFC 3339Rows at or before this time (optional)
limitqueryintegerMax rows returned, applied after sort (optional)
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/kalshi/deltas/KXBTC15M-26MAR281500-50?start_ts=2026-03-26T14:00:00Z"
Response 
{
  "exchange": "kalshi",
  "ticker": "KXBTC15M-26MAR281500-50",
  "count": 3,
  "rows": [
    {"ts": "2026-03-26T14:00:03.000Z", "sequence": 10021, "side": "bid", "price": "0.4800", "quantity_delta": "50.00"},
    {"ts": "2026-03-26T14:00:03.000Z", "sequence": 10022, "side": "ask", "price": "0.5200", "quantity_delta": "-80.00"},
    {"ts": "2026-03-26T14:00:04.100Z", "sequence": 10023, "side": "bid", "price": "0.4900", "quantity_delta": "120.00"}
  ]
}
sequence is the exchange-assigned sequence number for ordering events within the same timestamp. quantity_delta is a signed decimal string — negative values mean that quantity was removed from that level.

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Examples by exchange

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Kalshi

Kalshi tickers follow patterns like KXBTC-25 (event series) or KXBTC15M-26MAR281530-50 (15-minute micro contracts). 
# List all Kalshi tickers
curl -H "x-api-key: your_key" \
  http://data.graylayer.tech/api/kalshi/tickers

# Filter to a specific series
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/kalshi/tickers?prefix=KXBTC15M"

# Snapshot for a short-dated BTC contract
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/kalshi/snapshots/KXBTC15M-26MAR281530-50?limit=50"

# Deltas over a 1-hour window
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/kalshi/deltas/KXBTC-25?start_ts=2026-03-26T14:00:00Z&end_ts=2026-03-26T15:00:00Z"

# Full day of deltas
curl -H "x-api-key: ak_prod_abc123def456" \
  "http://data.graylayer.tech/api/kalshi/deltas/KXBTC-25?start_ts=2026-03-26T00:00:00Z&limit=10000"

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Polymarket US

Polymarket tickers are market slugs — lowercase hyphenated strings matching the market URL on polymarket.com. 
# List all recorded Polymarket slugs
curl -H "x-api-key: your_key" \
  http://data.graylayer.tech/api/polymarket_us/tickers

# Filter to election markets
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/polymarket_us/tickers?prefix=will-donald"

# Latest snapshot for a market
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/polymarket_us/snapshots/will-donald-trump-win-the-2024-us-presidential-election?limit=1"

# Historical snapshots over a time range
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/polymarket_us/snapshots/bitcoin-above-100000-on-december-31?start_ts=2026-03-01T00:00:00Z&end_ts=2026-03-02T00:00:00Z"

# Orderbook deltas for a crypto market
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/polymarket_us/deltas/will-bitcoin-reach-150k-in-2026?start_ts=2026-03-26T12:00:00Z&limit=500"

# Deltas for a political market
curl -H "x-api-key: ak_prod_abc123def456" \
  "http://data.graylayer.tech/api/polymarket_us/deltas/will-the-us-enter-a-recession-in-2026?start_ts=2026-03-01T00:00:00Z"
Snapshot response (Polymarket) 
{
  "exchange": "polymarket_us",
  "ticker": "will-bitcoin-reach-150k-in-2026",
  "count": 4,
  "rows": [
    {"ts": "2026-03-26T14:02:11.000Z", "side": "bid", "price": "0.3200", "quantity": "850.00"},
    {"ts": "2026-03-26T14:02:11.000Z", "side": "bid", "price": "0.3100", "quantity": "1200.00"},
    {"ts": "2026-03-26T14:02:11.000Z", "side": "ask", "price": "0.3400", "quantity": "500.00"},
    {"ts": "2026-03-26T14:02:11.000Z", "side": "ask", "price": "0.3500", "quantity": "2000.00"}
  ]
}
Delta response (Polymarket) 
{
  "exchange": "polymarket_us",
  "ticker": "will-bitcoin-reach-150k-in-2026",
  "count": 2,
  "rows": [
    {"ts": "2026-03-26T14:02:15.000Z", "sequence": 88421, "side": "bid", "price": "0.3200", "quantity_delta": "-150.00"},
    {"ts": "2026-03-26T14:02:16.000Z", "sequence": 88422, "side": "ask", "price": "0.3400", "quantity_delta": "300.00"}
  ]
}

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Gemini

Gemini has two classes of tickers:
  • Crypto spot pairs — e.g. BTCUSD, ETHUSD, SOLUSD
  • Prediction market contracts — instrumentSymbol values like GMKETSBTCUSD-20261231-T100000
# List all Gemini tickers
curl -H "x-api-key: your_key" \
  http://data.graylayer.tech/api/gemini/tickers

# Filter to BTC-related tickers
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/gemini/tickers?prefix=BTC"

# Filter to prediction market contracts
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/gemini/tickers?prefix=GMKETS"

# Snapshot for BTC/USD spot
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/gemini/snapshots/BTCUSD?limit=50"

# Snapshot for a prediction market contract
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/gemini/snapshots/GMKETSBTCUSD-20261231-T100000?limit=20"

# Deltas for ETH/USD over a window
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/gemini/deltas/ETHUSD?start_ts=2026-03-26T14:00:00Z&end_ts=2026-03-26T15:00:00Z&limit=1000"

# Deltas for a prediction market
curl -H "x-api-key: ak_prod_abc123def456" \
  "http://data.graylayer.tech/api/gemini/deltas/GMKETSBTCUSD-20261231-T100000?start_ts=2026-03-26T00:00:00Z"
Snapshot response (Gemini crypto spot) 
{
  "exchange": "gemini",
  "ticker": "BTCUSD",
  "count": 4,
  "rows": [
    {"ts": "2026-03-26T14:01:05.000Z", "side": "bid", "price": "87450.00", "quantity": "0.5000"},
    {"ts": "2026-03-26T14:01:05.000Z", "side": "bid", "price": "87400.00", "quantity": "1.2000"},
    {"ts": "2026-03-26T14:01:05.000Z", "side": "ask", "price": "87500.00", "quantity": "0.3000"},
    {"ts": "2026-03-26T14:01:05.000Z", "side": "ask", "price": "87550.00", "quantity": "2.1000"}
  ]
}

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Typical usage pattern

To reconstruct the book at a point in time and track it forward:
  1. Fetch a snapshot just before your target time to get the full book state
  2. Fetch deltas starting at that snapshot’s ts to replay changes forward
  3. Apply each delta: add quantity_delta to the existing quantity at (side, price); remove the level if quantity reaches zero
# 1. Get book state just before 14:00
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/kalshi/snapshots/KXBTC15M-26MAR281500-50?end_ts=2026-03-26T14:00:00Z&limit=500"

# 2. Replay changes from 14:00 onward
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/kalshi/deltas/KXBTC15M-26MAR281500-50?start_ts=2026-03-26T14:00:00Z"
Same pattern works across all exchanges: 
# Polymarket book reconstruction
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/polymarket_us/snapshots/will-bitcoin-reach-150k-in-2026?end_ts=2026-03-26T14:00:00Z&limit=500"

curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/polymarket_us/deltas/will-bitcoin-reach-150k-in-2026?start_ts=2026-03-26T14:00:00Z"

# Gemini book reconstruction
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/gemini/snapshots/BTCUSD?end_ts=2026-03-26T14:00:00Z&limit=500"

curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/gemini/deltas/BTCUSD?start_ts=2026-03-26T14:00:00Z"

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Cross-market queries

Compare the same question across exchanges: 
# BTC prediction — Kalshi
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/kalshi/snapshots/KXBTC-25?limit=1"

# BTC prediction — Polymarket
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/polymarket_us/snapshots/will-bitcoin-reach-150k-in-2026?limit=1"

# BTC spot — Gemini
curl -H "x-api-key: your_key" \
  "http://data.graylayer.tech/api/gemini/snapshots/BTCUSD?limit=1"

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Notes

  • Timestamps are UTC RFC 3339 (e.g. 2026-03-26T12:00:00Z)
  • side is "bid" or "ask"
  • quantity_delta can be negative (level removed or reduced)
  • Prices and quantities are decimal strings
  • Rows are always sorted ts ascending; limit truncates after sort
  • Send Accept-Encoding: gzip for smaller payloads — responses are gzip compressed
  • History begins from March 7, 2026