# StackBlitz WebContainers

Official pricing: https://stackblitz.com/pricing  
Category: dev-env · Isolation: v8-isolate

## Pricing regimes (raw)

- **Browser-local runtime licence** (sizes):  [alt]

## Features

Yes: snapshots, ≥24 h sessions, custom image (Docker or snapshot), start from your own snapshot, browser, HTTPS preview URLs, self-hosting, BYOC, SSO, Node.js, EU data residency, snapshots on demand, gVisor or VM (no shared kernel)

No: memory snapshots, fork/clone, pause/resume, persistent disk, volumes, idle auto-stop, your own Docker/OCI image, full VM (own kernel), Docker inside, nested virtualization, desktop GUI, computer-use API, browser + desktop control, anti-bot stealth, CAPTCHA solving, preinstalled agents, SSH, public IPv4, egress allowlist, static egress IP, open source, HIPAA, GPU, arm64, Windows, macOS, Python, HTTP method/path egress rules, wake on request, live resize, live fork (no pause), memory fork, MCP server, usage per sandbox (API), automatic snapshots, agent harness API, hosted agent API (their own agent), inbound access rules, firewall inside (nftables), secret proxy, secret proxy for any API, extra volumes, shared volumes, FUSE mounts, kernel features (eBPF, mounts, cgroups)

Unknown: everything else. Evidence (source + quote) per feature: https://battleships.dev/data/providers/webcontainers.json → feature_evidence

## Company

- Ownership: independent
- Stage: series-b [source](https://www.forbes.com/companies/stackblitz/)
- Accelerators: none found
- Total raised: $105M (confirmed: Forbes company profile, citing the Jan 2025 Series B close) [source](https://www.forbes.com/companies/stackblitz/)
- Last round: series-b, $83.5M, 2025-01, led by Emergence Capital, GV (Google Ventures) (confirmed) [source](https://www.bloomberg.com/news/articles/2025-01-21/ai-speech-to-code-startup-stackblitz-is-in-talks-for-a-700-million-valuation)
- Investors: Emergence Capital, GV (Google Ventures), Madrona Venture Group, Conviction, Mantis, Greylock, Tom Preston-Werner, Jay Srinivasan, Pratyus Patnaik
- Revenue: $4M (confirmed: company claim reported by Forbes) [source](https://www.forbes.com/companies/stackblitz/) ARR, 2024-11

WebContainers (webcontainers.io) is StackBlitz's in-browser Node.js/WebAssembly runtime technology, licensed commercially via StackBlitz's Enterprise plan; it is not an independently funded company. StackBlitz itself was 'on the verge of shuttering' before Bolt.new (launched Oct 2024, built on WebContainers) drove rapid growth and the Jan 2025 $83.5M Series B at a $700M valuation (Bloomberg/Forbes). Not a Y Combinator company (no YC profile found for StackBlitz). Prior seed round: $7.9M led by Greylock (2022, TechCrunch).

## Caveats

- In-browser Node.js/WebAssembly execution SDK, not a hosted Linux machine. Enterprise embedding/licensing is the purchasable product; end-user local CPU/RAM not billed as cloud vCPU-hours.
- Not fully priceable in ENGINE_CARD: unknown USD resource rates or machine shape. Null is not zero; do not rank as a free provider.
- Features set to null were not verified. No sandbox was purchased or tested; feature/performance statements are documentation claims. Null maximums are unknown unless a cited note explicitly states unlimited.
- A complete monthly bill requires known snapshot/egress/plan limits; do not silently treat missing ancillary charges as free.
- Licence metric is API sessions per month (free tier: up to 25,000, non-commercial with attribution); Enterprise has a custom session count at an unpublished price. Commercial use authenticates with an API key (configureAPIKey, API 1.3.0) obtained via the StackBlitz API console (stackblitz.com/api-console, login required). New StackBlitz ToS (published 2026-09-14, effective for existing accounts 2026-10-07) section 1.5(c) makes the session limits contractual.

## How this provider charges


As of 2026-09-28. Prices are USD unless explicitly labelled otherwise. Source type: official published list/promo or unknown, never a fabricated quote.

In-browser Node.js/WebAssembly execution SDK, not a hosted Linux machine. Enterprise embedding/licensing is the purchasable product; end-user local CPU/RAM not billed as cloud vCPU-hours.

| Regime | When it applies | How billed / numbers | Source |
|---|---|---|---|
| WebContainers API | Local browser execution | Commercial embedding licence; no hosted4/8 runtime rate. | https://webcontainers.io/enterprise |

## Gotchas

- In-browser Node.js/WebAssembly execution SDK, not a hosted Linux machine. Enterprise embedding/licensing is the purchasable product; end-user local CPU/RAM not billed as cloud vCPU-hours.
- Not fully priceable in ENGINE_CARD: unknown USD resource rates or machine shape. Null is not zero; do not rank as a free provider.
- Features set to null were not verified. No sandbox was purchased or tested; feature/performance statements are documentation claims. Null maximums are unknown unless a cited note explicitly states unlimited.
- A complete monthly bill requires known snapshot/egress/plan limits; do not silently treat missing ancillary charges as free.

## Worked workload

4 vCPU / 8 GiB; 50 simultaneous instances × 8 h/day × 22 days = **8,800 instance-hours**, **35,200 vCPU-hours**, **70,400 GiB-hours**. At 30% observed CPU:10,560 active-vCPU-hours only where the meter actually uses utilization. Assume one start/instance/day:1,100starts. Retain50GiB snapshots for a month;100GiB outbound. Active disk capacity was not specified.

The prescribed cloud4/8/50-concurrent workload is not comparable: execution consumes each client browser rather than provisioned Linux VMs. No normalized machine price.

## Sources

- https://webcontainers.io/enterprise
- https://webcontainers.io/