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microsandbox vs vercel sandbox

reviewed

microsandbox is the better fit for an open-source runtime with local memory checkpoints. Vercel Sandbox provides managed Firecracker sandboxes with project integration and active-CPU billing. [1][2][21][26]

both isolate workloads with a separate guest kernel. microsandbox can run the VM locally or use its private-beta cloud. calling Vercel’s SDK locally still executes the sandbox on Vercel’s infrastructure. [1][20][24]

Vercel now has persistent sandboxes that automatically save files between sessions. that is useful for agent workspaces, but a filesystem snapshot does not resume the old processes and memory. [3]

microsandbox
local + cloud
vercel sandbox
managed Firecracker sandboxes
local execution
macOS · Linux · Windows [26]
hosted execution; JavaScript and Python clients can run elsewhere [1]
runtime ownership
apache 2.0 runtime and SDKs [26]
managed service with open-source client tooling [1][6]
isolation
microVM with separate guest kernel [24]
Firecracker microVM [1]
SDKs
rust · typescript · python · go · ruby · CLI [25][26]
JavaScript/TypeScript · Python · CLI [1]
snapshots
local snapshots save disk state, or disk, memory, and running processes with --full. cloud currently supports disk snapshots from stopped persistent sandboxes and disk restore. [21]
filesystem snapshots; persistent sessions save automatically on stop [3][4]
firewall
public internet allowed by default; private and metadata destinations blocked. allowlist or disable egress; cloud keeps a non-public deny floor. [29]
domain and CIDR rules; live policy updates and request transforms [5]
credentials
placeholder in the guest; host-side substitution for allowed destinations in supported requests. an allowed endpoint can still expose the real secret. [28]
outbound header transforms and request-proxy rules [5]
billing
free local runtime · cloud free tier and paid plans [27]
Hobby quotas; paid usage includes active CPU, provisioned memory, storage, and transfer [2]
pick microsandbox

choose microsandbox when

  • you need execution on local machines or employee devices. [22][26]
  • you need to checkpoint and branch running local processes. [21]
  • you want runtime source and control without a hosted project dependency. [26]
pick vercel sandbox

choose vercel sandbox when

  • you want hosted sandboxes integrated with Vercel projects. [1]
  • you need its live firewall controls or persistent-session workflow. [3][5]

01

persistent files are not persistent memory

Vercel saves a persistent sandbox’s filesystem when its session stops. the next session boots from that snapshot; lifecycle hooks can restart services and rebuild caches. [3] microsandbox’s local full snapshots resume saved processes and memory in a new sandbox. compatible runtime and resource settings are required, and clients must reconnect. [21]

microsandbox cloud currently supports disk capture from stopped persistent sandboxes. full checkpoints and branching remain local. [20][21]

snapshot compatibility

02

active CPU is only part of the bill

Vercel does not charge active CPU time while code waits for I/O, but provisioned memory is still metered while the sandbox runs. storage, creation, and transfer charges also apply according to plan and region. [2] compare a whole session’s cost, not a CPU rate alone.

microsandbox’s local runtime has no usage charge. its managed cloud has separate plans and compute rates. [27]

microsandbox pricing

common questions

can Vercel Sandbox run locally?

you can call its clients locally, but the VM runs on Vercel. microsandbox runs the VM itself on macOS, Linux, or Windows. [1][26]

does Vercel Sandbox preserve memory?

its documented persistence model saves the filesystem and starts a new session from it. it does not describe resuming the previous process memory. microsandbox supports full disk-and-memory snapshots locally. [3][4][21]

is Vercel Sandbox free?

Hobby includes usage quotas. paid plans meter active CPU, provisioned memory, and other resources. waiting for I/O avoids active-CPU charges, not all charges. [2]

primary sources

  1. [1] Vercel Sandbox architecture and SDKs · last verified 2026-09-26
  2. [2] Sandbox pricing dimensions and quotas · last verified 2026-09-26
  3. [3] persistent sandboxes and session lifecycle · last verified 2026-09-26
  4. [4] filesystem snapshots and retention · last verified 2026-09-26
  5. [5] egress firewall and request transforms · last verified 2026-09-26
  6. [6] Vercel Sandbox client source · last verified 2026-09-26
  7. [20] microsandbox cloud availability and backend compatibility · last verified 2026-09-26
  8. [21] microsandbox disk snapshots, full checkpoints, and local branching · last verified 2026-09-26
  9. [22] microsandbox managed deployment with Jamf and Intune · last verified 2026-09-26
  10. [24] microsandbox microVM isolation · last verified 2026-09-26
  11. [25] microsandbox runtime, CLI, images, and language SDKs · last verified 2026-09-26
  12. [26] microsandbox source, Apache-2.0 license, and supported host platforms · last verified 2026-09-26
  13. [27] microsandbox cloud plans and usage pricing · last verified 2026-09-26
  14. [28] microsandbox credential substitution and its limits · last verified 2026-09-26
  15. [29] microsandbox host-side network defenses · last verified 2026-09-26

run it locally.

put the boundary on your own machine before you choose anything else.

run it locally