Advantage / disadvantage odds
API · /dicepool-api
Dice Probability API
healthy
3,594 Subscribers
Tabletop dice-probability maths as an API, computed locally and deterministically and exactly — the odds behind the rolls, not the rolls themselves. The advantage endpoint gives the D&D-style chances of beating a target on a d20 (or any die) rolling normally, with advantage (roll twice, keep the higher) or with disadvantage (keep the lower): needing an 11+ is 50 % normally, 75 % with advantage and 25 % with disadvantage, and it reports the average roll — advantage lifts a d20 from 10.5 to about 13.8. The pool endpoint handles success-counting systems (World of Darkness, Shadowrun): for a pool of dice that succeed on a face at or above a threshold it gives the chance per die, the expected number of successes and the exact binomial probability of getting exactly, or at least, a target number — six d10s succeeding on 7+ average 2.4 successes with a 45.6 % chance of three or more. The exploding endpoint gives the mean of an exploding ("acing", open-ended) die that re-rolls and adds on its maximum face — a d6 averages 4.2 instead of 3.5. Everything is computed locally and deterministically, so it is instant and private. Ideal for tabletop, virtual-tabletop, game-design and TTRPG app developers, odds-and-probability helpers, and game-master tools. Pure local computation — no key, no third-party service, instant. Exact maths, no simulation. Live, nothing stored. 3 compute endpoints. For random rolls use a dice-roller API.
api.oanor.com/dicepool-api
API health
healthy- Uptime
- 100.00%
- Server probes · 24h
- Avg latency
- 77 ms
- Server probes · 24h
- Subscribers
- 3,594
- active
- Total calls
- 0
- last 7 days
Pricing
Pick a tier — billed monthly, cancel anytime.
Free
Free
- 6,350 calls / month
- 2 requests / second
- Hard cap (429 above quota, no overage)
- 6,350 calls/month
- 2 req/sec
- Advantage + pool + exploding odds
- No credit card
Starter
€4.05 /month
- 58,000 calls / month
- 6 requests / second
- Hard cap (429 above quota, no overage)
- 58,000 calls/month
- 6 req/sec
- Binomial pools, any die, averages
- Email support
Pro
€11.30 /month
- 238,500 calls / month
- 15 requests / second
- Hard cap (429 above quota, no overage)
- 238,500 calls/month
- 15 req/sec
- Game-design & VTT pipelines
- Priority support
Mega
€36.00 /month
- 1,370,000 calls / month
- 40 requests / second
- Hard cap (429 above quota, no overage)
- 1,370,000 calls/month
- 40 req/sec
- Platform scale
- Dedicated SLA
Built by
Related APIs
Other APIs with overlapping tags.
Dice API
A fast, fully-local dice toolkit for games and simulations: roll dice notation (NdM with plus and minus modifiers, multiple dice terms like 1d8+1d6+2, and keep-highest or keep-lowest for advantage and disadvantage such as 2d20kh1), parse and validate a notation, and compute the deterministic minimum, maximum and mean of a roll. Rolls use a cryptographically secure random source. Every endpoint accepts input via the query string or the request body. Pure server-side compute, no third-party upstream, so responses are instant and always available. Ideal for tabletop and RPG tools, Discord and chat bots, virtual tabletops and game backends.
api.oanor.com/dice-api
Birthday Paradox API
Birthday-paradox and collision-probability maths as an API, computed locally and deterministically. The probability endpoint computes the chance that at least two of n people share a birthday among d equally likely days, P = 1 − Π(1 − i/d), evaluated in log space for accuracy — the famous result that just 23 people give about a 50.7 % chance, 50 people about 97 % and 70 people about 99.9 %. The people-needed endpoint inverts it: the smallest group size to reach a target probability (23 for 50 %, 57 for 99 %), with the √(2·d·ln(1/(1−p))) approximation. The collision endpoint generalises the birthday bound to any space — pass a number of buckets or a hash size in bits — and returns the collision probability P ≈ 1 − e^(−n²/2d), the rule behind hash collisions and UUID-uniqueness estimates, where a 50 % chance needs roughly 1.177·√d items. Days and buckets default to 365. Everything is computed locally and deterministically, so it is instant and private. Ideal for probability-education, security, cryptography, hashing, data-engineering and statistics app developers, collision-risk and birthday-problem tools, and teaching material. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the birthday/collision probability; for full distributions use a probability API.
api.oanor.com/birthdayparadox-api
Betting Odds API
Betting-odds maths as an API, computed locally and deterministically. The convert endpoint translates a price between every format used by bookmakers — decimal (European), fractional (UK), American (moneyline) and the implied probability — give it any one and it returns all the others, with the implied probability that the odds represent (1 ÷ decimal). The payout endpoint computes the profit and total return for a stake at given decimal or American odds. The parlay endpoint combines several decimal-odds selections into one accumulator by multiplying them, returning the combined odds, the implied probability and the payout for a stake — every leg must win, so the payout grows fast while the probability shrinks. Decimal odds are the total return per unit staked, American odds are at least +100 for an underdog or −100 or lower for a favourite, and fractional odds look like 5/2. Everything is computed locally and deterministically, so it is instant and private. Ideal for sports-betting, fantasy, odds-comparison and gaming app developers, bet-slip and value tools, and probability education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is odds conversion; for probability distributions use a probability API.
api.oanor.com/odds-api
Probability API
Probability distributions and combinatorics as an API. The binomial endpoint gives the probability of exactly k successes in n trials (PMF), the cumulative probability up to k (CDF), and the mean, variance and standard deviation. The poisson endpoint does the same for the Poisson distribution from a rate λ. The normal endpoint computes the z-score, probability density, cumulative probability (CDF) and percentile for a value under a normal distribution with any mean and standard deviation — and runs in reverse, turning a probability into the value (the quantile / inverse CDF) and its z-score. The combinatorics endpoint computes combinations (nCr), permutations (nPr) and factorials with exact big-integer arithmetic. Everything is computed locally and deterministically, so it is instant and private. Ideal for data science and statistics, quality control and A/B-test planning, gaming and gambling odds, risk modelling, and statistics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 5 endpoints. This is probability theory; for descriptive statistics on a dataset use a statistics API and for general expression evaluation use a math API.
api.oanor.com/probability-api
Frequently asked questions
Quick answers about pricing, quotas, and integration.
How do I get an API key for Dice Probability API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Dice Probability API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Dice Probability API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Dice Probability API cost?
Dice Probability API has a free tier with 100 calls / month. Paid plans start at €4.05 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Dice Probability API GDPR-compliant?
All requests to Dice Probability API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.
Pick an endpoint from the list on the left to see its details and try it.
Code snippets
Sign up to get an API key, then call any path under your slug.
curl https://api.oanor.com/dicepool-api/SOME_PATH \
-H "x-oanor-key: oanor_test_..."const res = await fetch("https://api.oanor.com/dicepool-api/SOME_PATH", {
headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();$ch = curl_init("https://api.oanor.com/dicepool-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);import requests
r = requests.get(
"https://api.oanor.com/dicepool-api/SOME_PATH",
headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())Ratings
Sign in to rate.
No reviews yet.
Discussion
Ask questions, share usage tips, get answers from the provider and other developers. Public — anyone can read.
Sign in to start a thread or reply.
Sign inNew thread
📌 Pinned
🔒 Locked
·
·
·
-
Provider answer
🔒 This thread is locked — no new replies.
-
·
- No threads yet — start the discussion.
Support
Private 1:1 support with the provider — billing questions, integration issues, account problems. Only you and the provider team can see these threads.
Sign in to open a support ticket.
Sign inOpen new ticket
Describe what you need help with. The provider team gets an email and replies on the ticket page.
-
·
Urgent - No tickets yet for this API.