Middles

Find middle opportunities where two sportsbooks have different lines, creating a gap where both bets can win.


GET /api/v1/opportunities/middles

AuthenticationPermalink for this section

Requires API key. Pro tier or higher required.

Query ParametersPermalink for this section

Parameter	Type	Default	Description
`sport`	string	all	Filter by sport(s), comma-separated (e.g. `basketball`, `football`)
`league`	string	all	Filter by league(s), comma-separated (e.g. `nba`, `nfl`, `nhl`)
`sportsbook`	string	tier-allowed	Filter by sportsbook(s), comma-separated. Tier limits enforced.
`market`	string	all	Filter by market type(s), comma-separated (e.g. `point_spread`, `total_points`). Supports category aliases — see Odds: Market Category Aliases.
`min_profit`	number	—	Minimum ROI % — filters by each middle’s `roi_percentage`
`live`	boolean	—	`true` = live only, `false` = prematch only, omit = both
`max_odds_age`	number	—	Max odds age in seconds. Filters out stale opportunities.
`sort`	string	`quality`	Sort field: `quality` (default), `ev`, `probability`, `middle_size`
`limit`	integer	50	Results per page (max 200)
`offset`	integer	0	Pagination offset (max 5000)

Example RequestsPermalink for this section

cURL


curl -X GET "https://api.sharpapi.io/api/v1/opportunities/middles?league=nfl&min_profit=1" \
  -H "X-API-Key: YOUR_API_KEY"

JavaScript


const response = await fetch(
  'https://api.sharpapi.io/api/v1/opportunities/middles?league=nfl&min_profit=1',
  { headers: { 'X-API-Key': 'YOUR_API_KEY' } }
);
const { data, meta } = await response.json();
 
for (const middle of data) {
  console.log(`${middle.event_name} [${middle.market_type}]`);
  console.log(`  Middle: ${middle.middle_size} pts, numbers: ${middle.middle_numbers}`);
  console.log(`  EV: $${middle.expected_value}, probability: ${(middle.middle_probability * 100).toFixed(1)}%`);
  if (middle.is_guaranteed_profit) {
    console.log(`  *** GUARANTEED PROFIT: ${middle.guaranteed_roi}% ROI ***`);
  }
  if (middle.key_numbers.length > 0) {
    console.log(`  Key numbers: ${middle.key_numbers} (${(middle.key_number_probability * 100).toFixed(1)}%)`);
  }
}

Python


import requests
 
response = requests.get(
    'https://api.sharpapi.io/api/v1/opportunities/middles',
    params={'league': 'nfl', 'min_profit': 1},
    headers={'X-API-Key': 'YOUR_API_KEY'}
)
data = response.json()
 
for middle in data['data']:
    print(f"{middle['event_name']} [{middle['market_type']}]")
    print(f"  Middle: {middle['middle_size']} pts at {middle['middle_numbers']}")
    print(f"  EV: ${middle['expected_value']}, prob: {middle['middle_probability']:.1%}")
    if middle['is_guaranteed_profit']:
        print(f"  *** GUARANTEED PROFIT: {middle['guaranteed_roi']}% ***")

ResponsePermalink for this section

Success (200)Permalink for this section

Real response for GET /api/v1/opportunities/middles?league=mlb&live=false&sort=middle_size&limit=1 (captured 2026-07-02; alt_side2 truncated for brevity):


{
  "data": [
    {
      "alt_side1": [
        {
          "book": "kalshi",
          "external_event_id": "KXMLBTOTAL-26JUL022210SDLAD",
          "market_id": "KXMLBTOTAL-26JUL022210SDLAD-4",
          "odds": -1329,
          "selection_id": "KXMLBTOTAL-26JUL022210SDLAD-4_yes"
        },
        {
          "book": "novig",
          "external_event_id": "019f1eb1-8730-7851-aab2-7d433205d1fc",
          "market_id": "019f20bb-5b05-7841-9c2c-e4fabf16bdcf",
          "odds": -3471,
          "selection_id": "019f20bb-5b05-7841-9c2c-e500de0ba6e2"
        }
      ],
      "alt_side2": [
        {
          "book": "kalshi",
          "external_event_id": "KXMLBTOTAL-26JUL022210SDLAD",
          "market_id": "KXMLBTOTAL-26JUL022210SDLAD-8",
          "odds": 182,
          "selection_id": "KXMLBTOTAL-26JUL022210SDLAD-8_no"
        },
        {
          "book": "novig",
          "external_event_id": "019f1eb1-8730-7851-aab2-7d433205d1fc",
          "market_id": "019f1eb1-8767-7393-9a85-b234a45f6e58",
          "odds": 170,
          "selection_id": "019f1eb1-8767-7393-9a85-b25a26e03f2c"
        }
      ],
      "away_team": "San Diego Padres",
      "best_case_profit": 89.75,
      "break_even_percent": 5.4,
      "detected_at": "2026-07-02T18:24:11Z",
      "event_id": "mlb_dodgers_padres_2026-07-02_b3",
      "event_name": "San Diego Padres @ Los Angeles Dodgers",
      "expected_value": 28.32,
      "guaranteed_roi": null,
      "home_team": "Los Angeles Dodgers",
      "id": "102f0c34a65c64b6",
      "is_guaranteed_profit": false,
      "is_live": false,
      "is_player_prop": false,
      "is_team_total": false,
      "key_number_probability": 0,
      "key_numbers": [],
      "league": "mlb",
      "league_label": "MLB",
      "market_label": "Total Runs",
      "market_overround": 1.054,
      "market_type": "total_runs",
      "middle_numbers": [
        4,
        5,
        6,
        7
      ],
      "middle_probability": 0.3525,
      "middle_size": 4,
      "odds_age_seconds": 546,
      "player_name": null,
      "quality_score": 1.84,
      "roi_percentage": 28.32,
      "side1": {
        "book": "polymarket",
        "external_event_id": "mlb_dodgers_padres_2026-07-02_b3",
        "fair_probability": 0.655,
        "line": 3.5,
        "market_id": "pm_2763202",
        "odds_age_seconds": 244.6,
        "odds_american": -223,
        "odds_decimal": 1.448,
        "odds_probability": 0.6904024767801857,
        "selection": "Over",
        "selection_id": "2763202_over",
        "stake_percent": 65.5
      },
      "side2": {
        "book": "sx_bet",
        "external_event_id": "L18646245",
        "fair_probability": 0.345,
        "line": 7.5,
        "market_id": "sx_0x5e051a0f483fc08b7b3d9d5893ca1970a90d693b8072be89ae272e5684be2c6d",
        "odds_age_seconds": 546,
        "odds_american": 175,
        "odds_decimal": 2.75,
        "odds_probability": 0.36363636363636365,
        "selection": "Under",
        "selection_id": "0x5e051a0f483fc08b7b3d9d5893ca1970a90d693b8072be89ae272e5684be2c6d_2",
        "stake_percent": 34.5
      },
      "sport": "baseball",
      "start_time": "2026-07-03T02:11Z",
      "stat_category": null,
      "team_name": null,
      "warnings": [
        "HIGH_PROBABILITY",
        "LARGE_GAP",
        "STALE_ODDS"
      ],
      "worst_case_loss": -5.13,
      "worst_case_pnl": -5.13
    }
  ],
  "pagination": {
    "count": 1,
    "has_more": true,
    "limit": 1,
    "next_offset": 1,
    "offset": 0,
    "total": 31
  },
  "updated_at": "2026-07-02T18:24:11.737562235Z"
}

Response HeadersPermalink for this section


X-RateLimit-Limit: 300
X-RateLimit-Remaining: 296
X-RateLimit-Reset: 1707401000
X-Data-Delay: 0
X-Request-Id: 1782526326424224-82519

Error ResponsesPermalink for this section

401 Unauthorized

No key supplied returns missing_api_key; a bad key returns invalid_api_key.


{
  "error": {
    "code": "missing_api_key",
    "message": "API key required. Pass via X-API-Key header, api_key query parameter, or Bearer token.",
    "docs": "https://sharpapi.io/docs/authentication"
  }
}

403 Tier Restricted


{
  "error": {
    "code": "tier_restricted",
    "message": "This endpoint requires Pro tier or higher",
    "docs": "https://sharpapi.io/pricing",
    "tier": "hobby",
    "required_tier": "pro"
  }
}

Response FieldsPermalink for this section

Field	Type	Description
`id`	string	Unique middle identifier (hash)
`event_id`	string	Event identifier
`event_name`	string	Human-readable event name
`sport`	string	Sport identifier
`league`	string	League identifier
`market_type`	string	Market type (`point_spread`, `total_points`, player prop types)
`market_label`	string	Human-readable market name
`league_label`	string	Human-readable league name
`home_team`	string	Home team name
`away_team`	string	Away team name
`start_time`	string\|null	Game start time (ISO 8601)
`side1`	object	First side of the middle bet
`side2`	object	Second side of the middle bet
`middle_size`	number	Size of the middle gap in points
`middle_numbers`	number[]	Integer values that would hit the middle
`middle_probability`	number	Estimated probability of the middle hitting. Sport- and market-specific: a per-sport multiplicative calibration factor (backtested against settled outcomes and refreshed as data accrues, most recently 2026-07-02) is applied to the raw per-number sum, then clamped to a ceiling of 0.50.
`expected_value`	number	EV in dollars per $100 total wagered
`roi_percentage`	number	EV as percentage of total stake
`worst_case_loss`	number	`worst_case_pnl` clamped to `<= 0` — the downside when the middle misses (`0` on guaranteed-profit middles, negative otherwise)
`worst_case_pnl`	number	Raw worst-case profit-and-loss per $100 total stake. Positive on guaranteed-profit middles (arb + middle — the worst case still profits), negative otherwise. Equals `worst_case_loss` only when negative.
`best_case_profit`	number	Profit when middle hits (both bets win)
`break_even_percent`	number	Minimum hit rate needed to break even
`odds_age_seconds`	number\|null	Age of stalest underlying odds at detection time
`is_guaranteed_profit`	boolean	True when `worst_case_loss >= 0` (arb + middle)
`guaranteed_roi`	number\|null	Worst-case ROI% when guaranteed (null otherwise)
`key_numbers`	number[]	Key numbers in middle range (e.g., NFL 3, 7)
`key_number_probability`	number	Combined probability of key numbers only
`quality_score`	number	Multi-factor quality metric (0-100)
`market_overround`	number	Combined implied probability across both sides
`is_live`	boolean	Whether the game is currently in-play
`is_player_prop`	boolean	Whether this is a player prop middle
`player_name`	string\|null	Player name (if player prop)
`stat_category`	string\|null	Stat type (if player prop, e.g., `points`, `rebounds`)
`is_team_total`	boolean	Whether this is a team-total middle
`team_name`	string\|null	Team name (if team total)
`alt_side1`	object[]	Other books offering side 1’s selection at the same line — `{book, odds, selection_id, market_id, external_event_id}` per entry, sorted best price first. Empty array when no alternates.
`alt_side2`	object[]	Other books offering side 2’s selection at the same line (same shape as `alt_side1`)
`warnings`	string[]	Warning flags (see below)
`detected_at`	string	When the middle was detected (ISO 8601)

Side ObjectPermalink for this section

Field	Type	Description
`book`	string	Sportsbook for this side
`selection`	string	The selection name
`line`	number	The line value at this sportsbook
`odds_american`	number	American odds
`odds_decimal`	number	Decimal odds
`odds_probability`	number	Implied probability (0-1)
`fair_probability`	number	Fair probability adjusted for overround
`stake_percent`	number	Recommended stake allocation (% of total)
`odds_age_seconds`	number\|null	Age of this side’s odds at detection time
`selection_id`	string\|null	Sportsbook’s native selection/outcome ID
`market_id`	string\|null	Sportsbook’s native market ID
`external_event_id`	string\|null	Sportsbook’s native event ID
`home`	object\|undefined	Reserved — not currently emitted on this endpoint. Nested home-team reference: `{id, numerical_id, name, abbreviation, logo, city, mascot, conference, division}`. See Entity reference IDs.
`away`	object\|undefined	Reserved — not currently emitted on this endpoint. Nested away-team reference (same shape as `home`).
`sport_ref`	object\|undefined	Reserved — not currently emitted on this endpoint. Nested sport reference: `{id, numerical_id, name}`.
`league_ref`	object\|undefined	Reserved — not currently emitted on this endpoint. Nested league reference: `{id, numerical_id, label}`.
`market_ref`	object\|undefined	Reserved — not currently emitted on this endpoint. Nested market reference: `{id, numerical_id, label}`.
`sportsbook_ref`	object\|undefined	Reserved — not currently emitted on this endpoint. Nested sportsbook reference for this side’s book: `{id, numerical_id, label}`.

Nested reference blocks on each side (reserved)Permalink for this section

The side schema reserves six nested reference objects (home, away, sport_ref, league_ref, market_ref, sportsbook_ref) mirroring the blocks on /odds. As of 2026-07-02 the middles engine does not stamp them, so live side1 / side2 objects never include these blocks — today they appear only on /odds rows for atlas-mapped books. Treat every block (and every inner field) as optional and never require them; when emitted they will be purely additive — the flat top-level fields (sport, league, home_team, away_team, market_type) and per-side book / selection strings are unchanged. See Entity reference IDs for the shape and guarantees.

Warning FlagsPermalink for this section

Warning	Meaning
`HIGH_PROBABILITY`	Calibrated middle probability exceeds 35% — at or beyond the highest empirically realized hit rate; treat as notable (and double-check the lines)
`LARGE_GAP`	Middle size exceeds 3 points — verify lines are correct
`STALE_ODDS`	One or both odds are older than 300 seconds (5 minutes)
`LIVE_GAME`	Game is currently in progress
`GUARANTEED_PROFIT`	Worst-case loss is positive — this is also an arbitrage

Detail EndpointPermalink for this section

Fetch a single middle opportunity by its ID.


GET /api/v1/opportunities/middles/:id

Parameter	Type	Description
`id`	path	Required. 16-character hex hash (e.g., `a1b2c3d4e5f67890`)

Returns { "data": <middle>, "updated_at": "<ISO>" } — the middle uses the same schema as the list items. Returns 404 if the ID is unknown or malformed.


curl -X GET "https://api.sharpapi.io/api/v1/opportunities/middles/a1b2c3d4e5f67890" \
  -H "X-API-Key: YOUR_API_KEY"

What Are Middles?Permalink for this section

A middle occurs when two sportsbooks offer different lines on the same market, creating a numerical gap where both bets can win simultaneously.

Unlike arbitrage (which guarantees profit), middles give you a chance to win both sides of a bet if the final result lands in the “middle” of the two lines.

Spread Middle ExamplePermalink for this section


DraftKings:  Chiefs -2.5  @ -110
FanDuel:     Bills  +7.5  @ -108

You bet:

Chiefs -2.5 at DraftKings
Bills +7.5 at FanDuel

Possible outcomes:

Chiefs Win By	Chiefs -2.5	Bills +7.5	Result
1-2 points	Lose	Win	Split (small loss)
3, 4, 5, 6, or 7	Win	Win	MIDDLE HIT
8+ points	Win	Lose	Split (small loss)

If the Chiefs win by 3-7, both bets win. The numbers 3 and 7 are NFL key numbers (field goal and touchdown), making this middle especially valuable.

Key NumbersPermalink for this section

Certain sports have scoring increments that spike the probability distribution:

Sport	Key Numbers	Why
NFL	3, 7, 10, 14	Field goal (3), touchdown (7), combinations
NHL	1	Most games decided by 1 goal (~47%)
MLB	1	Most games decided by 1 run (~30%)
Soccer	1	Most matches decided by 1 goal (~38%)

When a middle contains key numbers, the key_numbers and key_number_probability fields highlight this. An NFL middle spanning 3 and 7 has a combined key number probability of ~24.2%.

Guaranteed Profit (Arb + Middle)Permalink for this section

When is_guaranteed_profit is true, the middle is also an arbitrage — the worst case still yields a profit. This is the rarest and most valuable type of middle. The guaranteed_roi field shows the minimum return even if the middle misses.

Middle Size GuidePermalink for this section

Middle Size	Quality	Typical Markets
0.5 points	Narrow	Rare opportunities, low hit rate
1.0 points	Standard	Common in spreads and totals
1.5 - 2.0 points	Good	Look for these actively
2.5+ points	Excellent	Uncommon but highly profitable

Sort by middle_size to surface the widest gaps first, and use min_profit for a minimum-ROI floor. Larger middles have a higher probability of landing in the gap, making them more consistently profitable over time.

Risk ConsiderationsPermalink for this section

Middles are not risk-free like arbitrage (unless is_guaranteed_profit is true). When the result falls outside the middle, you lose the vig on the losing side (typically 4-5% of one leg). However, when a middle hits, you win both bets, which more than compensates over time.

Odds FreshnessPermalink for this section

The odds_age_seconds field shows how old the underlying odds were when the middle was detected. Each side also has its own odds_age_seconds. If the stalest side exceeds 300 seconds (5 minutes), the STALE_ODDS warning is added. Stale odds may have already moved — act quickly on fresh opportunities.

Best PracticesPermalink for this section

Focus on larger middles — Sort by middle_size and prefer wider gaps for better hit rates
Watch for key numbers — Middles containing NFL 3/7 or NHL/MLB/soccer 1 have elevated hit rates
Prioritize guaranteed profit — Filter for is_guaranteed_profit to find risk-free opportunities
Check odds freshness — Low odds_age_seconds means the lines are current and actionable
Combine with the summary endpoint — Use /middles/summary for dashboard overviews
Act quickly — Lines converge as books adjust, closing the middle window
Use streaming — Subscribe to middles:detected events via SSE or WebSocket for real-time alerts

Middles Summary — Aggregate statistics without the full list
+EV Opportunities — Positive expected value bets
Arbitrage Opportunities — Guaranteed profit opportunities
SSE Stream — Real-time middles:detected and middles:expired events
Best Odds — Compare odds across all books