Runtime

Blaxel vs Prime Sandboxes: big fleets compared

Blaxel and Prime both aim at very large fleets of sandboxes. On the 2 vCPU, 4 GB benchmark Blaxel costs $2.76 and Prime $1.52.

Runtime charges 77% less than Blaxel and 58% less than Prime for the same job: 1,000 one-minute runs of a 2 vCPU, 4 GiB sandbox, each with 20 CPU-seconds of work. Blaxel prices memory alone, Prime prices every resource while it runs, and Runtime prices the CPU the code used.

Estimated compute cost

77% less than Blaxel58% less than Prime Sandboxes

2 vCPUs · 4 GiB · 60 s a run · 20 CPU-seconds busy

1,000

Compute only, at list rates checked 23 September 2026 and 25 September 2026 (Blaxel pricing, Prime Sandboxes overview). Plan fees, network, taxes and free credits are left out. The worked example below shows the arithmetic.

At a glance

Blaxel Prime Sandboxes Runtime
Isolation Lightweight virtual machines Hardware-virtualized microVM, own guest kernel Firecracker microVM, own kernel
Billing $0.0000115 per GB-second active, CPU included $0.02 per vCPU-hour, $0.0125 per GiB-hour $0.025 per measured vCPU-hour, $0.0075 per GiB-hour
Fleet Over 100,000 at once on the top tier 1,024 per account to start 100 paid; 50 for a new account's first week
Idle Standby when connections close; ~25 ms resume Idle timeout off by default, up to 24 hours Pause or idle pause, memory kept 1 to 365 days
Free start Up to $200 of credit None published 100 sandbox hours, no card

Standby against low rates

Blaxel makes idle sandboxes nearly free by dropping them to standby the moment their connections close. Prime makes running sandboxes cheap per hour but keeps billing until the sandbox ends or its optional idle timeout fires. Runtime's idle pause, set with idlePauseSeconds, stops compute billing too, and keeps memory for when the next request wakes it.

Cost for the same job

The benchmark, 60 seconds a run (4 GB of active memory on Blaxel, a 5 GiB disk on Prime):

TextBlaxel   Memory 1,000 × 60 s × 4 × $0.0000115                 = $2.76Prime    CPU    1,000 × 60 s / 3,600 × 2 × $0.02              = $0.67         Memory 1,000 × 60 s / 3,600 × 4 × $0.0125            = $0.83         Disk   1,000 × 60 s / 3,600 × 5 × $0.0002            = $0.02         Total                                                  $1.52Runtime  CPU    1,000 × 20 s / 3,600 × $0.025                = $0.14         Memory 1,000 × 60 s / 3,600 × 4 × $0.0075           = $0.50         Total                                                  $0.64

With both CPUs busy for the whole minute, the totals are $2.76 on Blaxel, $1.52 on Prime and $1.33 on Runtime.

Which one to pick

  • Blaxel for fleets of mostly idle sandboxes that resume in milliseconds.
  • Prime Sandboxes for dense RL training runs.
  • Runtime for the lowest cost while sandboxes run, and cheap paused storage.

See Runtime vs Blaxel and Runtime vs Prime Sandboxes.

Sources

Blaxel rates checked 23 September 2026; Prime Sandboxes rates checked 25 September 2026.

Facts on this page were checked on 25 September 2026.

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