Reserved Capacity

Reserved capacity lets you pre-commit to memory you'll use later. OpenComputer plans for it instead of holding margin against uncertain demand; you get a lower effective rate on the committed usage. Pure on-demand still works for everything else.

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Reservations are non-refundable

Once you commit to capacity for an interval, that's a permanent commitment. There is no cancellation, no transfer, no partial refund. The commitment is the whole reason the rate is lower — any carve-out re-introduces the demand risk reserved capacity exists to remove.

The hedge is to book conservatively: reserve only what you're confident you'll run, and let on-demand absorb everything else.

The unit is 1 GB-hour

Reservations are made against 15-minute UTC intervals on the quarter-hour grid: :00, :15, :30, :45. Within each interval, the minimum commitment is 4 GB for 15 minutes — that is, 1 GB-hour. All reservations must be multiples of 4 GB per interval; anything smaller isn't a meaningful commitment unit and the API rejects it.

The 15-minute time grain is deliberate. Reserve the slots you'll actually run in — you aren't pushed into a long contiguous block and asked to pay for the troughs in between. A nightly batch reserves the eight intervals it occupies; a weekday workload reserves working hours and skips evenings and weekends. The reserved rate applies whatever shape your demand takes.

You don't book individual blocks or get block IDs back. You just tell the API "for this interval, add this many GB to my reserved capacity," and the calendar shows you the new total.

A small example

Reserve 16 GB for the 02:00–02:15 UTC slot tomorrow:

curl

12345678910111213curl -X POST https://app.opencomputer.dev/api/capacity/reservations \
  -H "X-API-Key: $OPENCOMPUTER_API_KEY" \
  -H "Idempotency-Key: demo-1" \
  -H "Content-Type: application/json" \
  -d '{
    "intervals": [
      {
        "startsAt": "2026-04-29T02:00:00Z",
        "endsAt":   "2026-04-29T02:15:00Z",
        "capacityGb": 16
      }
    ]
  }'

Response:

json

1234567891011{
  "reservationId": "9f67b8f7-7b91-4d2d-b1cb-19d0d0a14562",
  "createdAt": "2026-04-28T18:00:05Z",
  "intervals": [
    {
      "startsAt": "2026-04-29T02:00:00Z",
      "endsAt":   "2026-04-29T02:15:00Z",
      "capacityGb": 16
    }
  ]
}

That's it. Run sandboxes normally during 02:00–02:15; they'll be allocated against your reserved capacity automatically. Anything over 16 GB during that interval falls back to on-demand rates.

Why reserve instead of running on-demand?

	On-demand (instant)	Reserved (pre-booked)
Rate	$0.060/GB-hour	$0.012/GB-hour
Commitment	None	Full — you pay regardless of usage
Availability	Subject to platform headroom	Guaranteed for the interval you booked
Best for	Unpredictable or bursty workloads	Nightly batch jobs, scheduled runs, known traffic patterns

If you already know you'll run 48 GB of agents at 3am every night, reserve the day before, get the lower rate, get the guarantee. If your workload is "whatever users ask for," stay on-demand. And because the granularity is 15 minutes, you can be precise — reserve the peaks, leave the troughs to on-demand, and don't commit to capacity outside your actual workload window.

Where to go next

Concepts

The vocabulary: intervals, reservations, the reservation log.

Reading the calendar

Plan reservations before you commit.

Reserving capacity

The write flow, idempotency, atomicity.

Usage and overage

How reserved capacity is consumed and how overage is billed.

Full endpoint reference: /api/capacity/*.

Pricing. Pre-booked capacity bills at $0.012/GB-hour; instant (overage) bills at $0.060/GB-hour — a 5× ratio that's the price of optionality for capacity you didn't pre-commit. Both rates are flat across sandbox sizes. Disk above the 20 GB allowance is billed separately at the disk-overage rate (unchanged).