# Reliability Engineering API > Reliability-engineering maths as an API, computed locally and deterministically — the availability, MTBF and failure maths behind SLAs and dependable systems. The availability endpoint converts between MTBF and MTTR, a target availability and the SLA "nines": give it a mean time between failures and a mean time to repair and it returns the availability A = MTBF/(MTBF+MTTR) and the downtime per year, month, week and day; give it a number of nines and it returns the budget — three nines (99.9 %) is 8.76 hours of downtime a year, five nines (99.999 %) just 5.26 minutes. The reliability endpoint computes the probability a unit survives a mission time under the exponential model R(t) = e^(−λt) with its constant hazard λ = 1/MTBF, or the Weibull model R(t) = e^(−(t/η)^β) — β below one for infant mortality, one for random failures, above one for wear-out — returning the reliability, failure probability, hazard rate and the mean life η·Γ(1+1/β). The system endpoint combines component reliabilities into a system: series (the weakest link, ΠRᵢ), parallel redundancy (1−Π(1−Rᵢ)) or k-of-n voting. Everything is computed locally and deterministically, so it is instant and private. Ideal for SRE, DevOps, hardware-reliability, safety-engineering and SLA-planning app developers, uptime-budget and redundancy-design tools, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. This is reliability and availability maths; for queue wait-times use a queueing API and for live uptime checks use a monitoring service. ## Authentication All requests require your oanor API key in the `x-oanor-key` header. Get one at https://www.oanor.com/developer/keys. ```bash curl -H "x-oanor-key: oanor_live_…" "https://api.oanor.com/reliability-api/..." ``` ## Pricing - **Free** (Free) — 4,150 calls/Mo, 2 req/s - **Starter** ($6/Mo) — 43,000 calls/Mo, 6 req/s - **Pro** ($17/Mo) — 198,000 calls/Mo, 15 req/s - **Mega** ($51/Mo) — 1,140,000 calls/Mo, 40 req/s ## Endpoints ### Reliability #### `GET /v1/availability` — Availability & downtime **Parameters:** - `mtbf` (query, optional, string) — Mean time between failures (h) Example: `1000` - `mttr` (query, optional, string) — Mean time to repair (h) Example: `10` - `availability` (query, optional, string) — Target availability (% or 0–1) - `nines` (query, optional, string) — Number of nines (e.g. 5) **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/reliability-api/v1/availability?mtbf=1000&mttr=10" ``` **Response:** ```json { "data": { "mtbf": 1000, "mttr": 10, "note": "Availability A = MTBF/(MTBF+MTTR). Three nines (99.9%) is 8.76 h/year of downtime; five nines (99.999%) is about 5.26 min/year.", "inputs": { "mtbf": 1000, "mttr": 10 }, "downtime": { "per_year_hours": 86.7327, "per_day_seconds": 855.4455, "per_week_minutes": 99.802, "per_month_minutes": 433.6634 }, "availability": 0.99009901, "nines_equivalent": 2.0043, "availability_percent": 99.009901 }, "meta": { "timestamp": "2026-06-05T21:48:49.267Z", "request_id": "4a14f2c3-ff8c-405c-99cf-79153bd81b1b" }, "status": "ok", "message": "Availability", "success": true } ``` #### `GET /v1/reliability` — Reliability at mission time **Parameters:** - `time` (query, required, string) — Mission time Example: `100` - `mtbf` (query, optional, string) — MTBF (exponential or Weibull scale) Example: `1000` - `failure_rate` (query, optional, string) — Constant failure rate λ - `beta` (query, optional, string) — Weibull shape β - `eta` (query, optional, string) — Weibull scale η **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/reliability-api/v1/reliability?time=100&mtbf=1000" ``` **Response:** ```json { "data": { "mtbf": 1000, "note": "Exponential R(t) = exp(−λt) with constant hazard λ = 1/MTBF — the memoryless 'useful life' part of the bathtub curve.", "model": "exponential", "inputs": { "mtbf": 1000, "time": 100, "failure_rate": 0.001 }, "hazard_rate": 0.001, "reliability": 0.904837418, "failure_probability": 0.095162582 }, "meta": { "timestamp": "2026-06-05T21:48:49.358Z", "request_id": "e77de998-2db3-42be-bb05-028412a81d79" }, "status": "ok", "message": "Reliability", "success": true } ``` #### `GET /v1/system` — System reliability **Parameters:** - `config` (query, optional, string) — series, parallel or kofn Example: `parallel` - `reliabilities` (query, required, string) — Comma-separated 0–1 list Example: `0.9,0.8,0.95` - `k` (query, optional, string) — k for k-of-n **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/reliability-api/v1/system?config=parallel&reliabilities=0.9%2C0.8%2C0.95" ``` **Response:** ```json { "data": { "note": "Series = ΠRᵢ (weakest-link); parallel = 1−Π(1−Rᵢ) (redundancy); k-of-n uses identical components R and the binomial of i≥k working.", "inputs": { "config": "parallel", "reliabilities": [ 0.9, 0.8, 0.95 ] }, "components": 3, "system_reliability": 0.999, "system_failure_probability": 0.001 }, "meta": { "timestamp": "2026-06-05T21:48:49.456Z", "request_id": "d742da98-7197-4a24-88c0-f65c6b7e1682" }, "status": "ok", "message": "System reliability", "success": true } ``` ### Meta #### `GET /v1/meta` — Spec **Example:** ```bash curl -H "x-oanor-key: $KEY" \ "https://api.oanor.com/reliability-api/v1/meta" ``` **Response:** ```json { "data": { "notes": "Use consistent time units (hours by default for MTBF/MTTR). Availability assumes a year of 8760 h. For queueing/wait times use a queue API.", "service": "reliability-api", "endpoints": { "GET /v1/meta": "This document.", "GET /v1/system": "System reliability from component reliabilities (series, parallel, k-of-n).", "GET /v1/reliability": "Reliability, failure probability and hazard rate at a mission time (exponential or Weibull).", "GET /v1/availability": "Availability and downtime from MTBF/MTTR, a target availability, or nines." }, "description": "Reliability engineering: availability & SLA nines, exponential/Weibull reliability, and series/parallel/k-of-n system reliability." }, "meta": { "timestamp": "2026-06-05T21:48:49.522Z", "request_id": "08db6d22-4440-43ff-bbe6-3ff5ae4a8346" }, "status": "ok", "message": "Meta", "success": true } ``` --- Marketplace page: https://www.oanor.com/api/reliability-api OpenAPI spec: https://www.oanor.com/api/reliability-api/openapi.json