This page covers the historical RunKit product. Current hosted availability and prices remain unverified; the linked vendor article dates from 2018 and is not a shutdown announcement. Read the source ↗

Development environments / RunKit alternative

RunKit alternative

This page covers RunKit’s historical cloud Node.js notebooks, embeds and endpoints. Official technical articles from 2015 and 2018 explain that design. Current hosted availability, support and prices remain unverified; confirm present service access before depending on a new integration.

Start buildingCompare capabilities ↓

Reviewed 2026-10-18 · Published by the Sandbox0 team

When RunKit fits

RunKit’s historical design suited interactive Node.js exploration, npm examples and embeddable executable documentation. If an existing integration remains accessible, preserve its exported code and required artifacts. Confirm current hosted support and commercial terms before relying on it.

When to consider Sandbox0

Consider Sandbox0 for a supported runtime environment that retains installed Linux tools, configuration and growing whole RootFS across agent tasks. Rebuild the notebook UI, embeds, endpoint routing and package/version handling as needed; those user-facing features do not follow automatically from a persistent computer.

Capabilities

RunKit and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimeRunKitNot established in this reviewSandbox0ttl and hard_ttl default to 0 (disabled). Configure idle pause and deletion policies for the same persistent sandbox identity; an idle running sandbox still accrues compute charges.Read documentation →
Persistent filesRunKitHistorical container filesystem commits are documented; current hosted durability and access were not verified.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSRunKitThe historical container-commit design is acknowledged; a current full writable Linux RootFS contract is not established.View evidence ↗Sandbox0Persistence extends beyond /workspace to paths such as /usr/local, /etc, and /home. Runtime tmpfs and virtual filesystems are excluded.Read documentation →
Release compute, keep stateRunKitHistorical notebook time travel is documented, but a current general-purpose hosted pause/resume contract is unverified.View evidence ↗Sandbox0Pause compute between tasks; resume on available capacity. Default resume starts fresh processes from the saved filesystem.Read documentation →
Memory and process stateRunKitThe 2015 article explicitly describes process-memory checkpoints; current commercial availability and compatibility are unverified.View evidence ↗Sandbox0Experimental memory checkpoints can preserve compatible process state. Use memory: true on both pause and resume on a compatible deployment. A filesystem checkpoint alone does not preserve running processes.Read documentation →

Online RootFS growth

On growth-enabled images, Sandbox0 automatically expands the writable RootFS as free space runs low, within a configured sparse logical ceiling up to 64 TiB. Agent processes keep running. Growth is enabled in the qualified Cloud region; confirm activation for other regions. Existing images and snapshots retain their captured storage geometry. The ceiling is logical capacity, not preallocated host disk.

RunKit historically checkpointed Node processes and committed container filesystem changes. The reviewed material does not establish a current automatically growing Linux RootFS contract. Sandbox0’s whole writable RootFS includes installed tools and system configuration for returning agent environments.

Files while compute is paused

Sandbox0's Files API reads persistent files without resuming compute. Filesystem-only pauses also permit edits; retained-memory pauses are read-only and reject mutations with 409. SSH, SFTP, file watching, and runtime-only mounts require running compute.

A RunKit notebook export or historical checkpoint is not evidence of a current API for reading and modifying the whole paused Linux RootFS. Recover needed code and file artifacts from available exports before designing the replacement.

See paused file operations →

Historical time travel included memory and filesystem state

RunKit’s 2015 engineering post describes CRIU checkpoints for the Node process tree and container filesystem commits, enabling notebook cells to rewind. That historical design includes process and filesystem state; it does not establish current hosted availability, retention limits or checkpoint compatibility.

Source 1 ↗

The product deliberately focused on JavaScript

The 2018 article describes a coherent JavaScript experience, immediate npm access, notebooks, zero-deploy endpoints and embeddable examples. Migrating to a Linux runtime can broaden tooling, but requires rebuilding any notebook execution/rendering semantics and preserving exact package versions rather than just copying visible cell output.

Source 1 ↗

Historical free pricing is not a current compute quote

A February 2017 answer in the official RunKit forum described the service as entirely free. That dated report does not verify current billing, quotas, support or hosted access. Obtain present commercial terms before treating the historical offer as a production option.

Source 1 ↗Source 2 ↗

Pricing

Compare billing models, then price your workload

CPU allocation, memory, billing minimums, disk, plan fees, and supported workload differ. These meters are not equal-performance machine quotes. Confirm region, resource units, and included allowances before estimating a total.

RunKit

Pricing reviewed 2026-10-18

Historical forum offer, February 2017
Reported free then; not a current price
A dated forum answer, not a current hosting, quota or support commitment.
Rate source ↗
Current hosted resources
No current rate verified
Confirm actual service access and terms before relying on any historical offer.
Rate source ↗

The cited historical materials do not establish a current hosted tariff or vendor shutdown announcement. Historical free use is not a current VM-hour, retained-storage or always-on endpoint quote.

Check current RunKit pricing ↗

Sandbox0

$0.015/GiB-hour compute (billed by the second at approximately $0.000004167/GiB-second), plus $0.02/GiB-month of retained incremental RootFS and memory checkpoint data. Shared base images and platform recovery retention are excluded; paused sandboxes accrue storage charges only.

Compute / GiB-hour
$0.015
Retained data / GiB-month
$0.02
Paused compute
$0.00

A 4 GiB agent, 100 running hours

$6.00 compute

4 GiB × 100 hours, billed by the second. Keeping 20 GiB of billable incremental data for a full billing month adds $0.40. CPU is derived from memory by the platform; choose a tier that fits your workload.

Understand storage billing →

Before migrating from RunKit

  1. Collect exported or locally saved JavaScript, dependency versions, endpoint behavior and file artifacts; use live exports only if access still works.
  2. Port code and required packages to a Sandbox0 template, rebuilding notebook/embed rendering and HTTP routing that the application actually needs.
  3. Validate Node behavior, state transitions, retained tools/files, RootFS growth, paused access and a current runtime/storage budget.

Common questions

Is Sandbox0 a drop-in RunKit replacement?

Evaluate API compatibility and product scope. These products serve different core workflows, so a change may require a different architecture.

Does keeping files also keep a running agent?

Filesystem state and volatile process state are separate. Sandbox0 requires explicit compatible memory checkpoints to preserve running processes; its default filesystem resume starts fresh processes.

Sources and review scope

The Boat team's Battleships directory is the discovery source. References below describe the product and plan discussed on this page. Check current availability, regional terms and billing units before migrating. Where the cited material does not establish a capability or price, the comparison identifies that uncertainty.

Battleships research record ↗blog.runkit.com/2015/09/10/time-traveling-in-node.js-notebooks.html ↗blog.runkit.com/2018/02/06/runkit-is-joining-tc39/ ↗discuss.runkit.com/t/why-the-name-change/251 ↗runkit.com/ ↗Sandbox0 RootFS capacity →

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