emulate provides local, stateful replacements for APIs and services so software can run in CI or environments without network access. It is used by developers who need production-like integrations with services such as GitHub, Stripe, AWS, Slack, and databases during testing. Its catalogue skills and instruction support agent workflows that use these local emulators.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add vercel-labs/emulate --skill stripegit clone --depth 1 https://github.com/vercel-labs/emulateWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/vercel-labs/emulate/stripe)<a href="https://agentmods.dev/skills/vercel-labs/emulate/stripe"><img src="https://agentmods.dev/badge/skills/vercel-labs/emulate/stripe/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/vercel-labs/emulate/stripe"><img src="https://agentmods.dev/badge/skills/vercel-labs/emulate/stripe.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 3 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium MCP Rug Pull · line 4 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 17 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium Data Exfiltration · line 135 Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00102 | $0.02861 |
| Opus 5.5 | $0.00041 | $0.01144 |
| Sonnet 5.5 | $0.00020 | $0.00572 |
| Haiku 4.5 | $0.00010 | $0.00286 |
Grade A, and why
stripe scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 21d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
allowed-tools: Bash(npx emulate:*), Bash(curl:*) Copies of this mod
1 near-identical copy found in the catalogue:
- stripe — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 393 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Stripe API Emulator
Fully stateful Stripe API emulation. Customers, products, prices, checkout sessions, payment intents, charges, and payment methods persist in memory. Webhooks fire on state changes. The hosted checkout UI lets you complete payments in the browser.
No real payments are processed. Every Stripe SDK call hits the emulator and produces realistic responses.
Start
Local listeners bind to 127.0.0.1 by default. For access from containers or other machines, pass --host 0.0.0.0 to the CLI or hostname: '0.0.0.0' to createEmulator. Configure --base-url or baseUrl for advertised URLs reachable by those clients.
# Stripe only
npx emulate --service stripe
# Default port (when run alone)
# http://localhost:4000
Or programmatically:
import { createEmulator } from 'emulate'
const stripe = await createEmulator({ service: 'stripe', port: 4000 })
// stripe.url === 'http://localhost:4000'
Pointing Your App at the Emulator
Stripe SDK
The Stripe Node.js SDK does not read an environment variable for the base URL. You must pass it when constructing the client:
import Stripe from 'stripe'
const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!, {
apiVersion: '2024-12-18.acacia',
host: 'localhost',
port: 4000,
protocol: 'http',
})
Embedded in Next.js (adapter-next)
When using @emulators/adapter-next, the emulator runs inside your Next.js app at /emulate/stripe. The SDK needs to point at localhost with a proxy route to forward /v1/* calls to /emulate/stripe/v1/*:
// next.config.ts
import { withEmulate } from '@emulators/adapter-next'
export default withEmulate({
env: {
STRIPE_SECRET_KEY: 'sk_test_emulated',
},
})
// lib/stripe.ts
import Stripe from 'stripe'
const port = process.env.PORT ?? '3000'
export const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!, {
apiVersion: '2024-12-18.acacia',
host: 'localhost',
port: parseInt(port, 10),
protocol: 'http',
})
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 21d ago Changed · +2 lines 1fb6e61d1b75
- 29d ago Changed · +4 lines e7e3322fa6a6
- 1mo ago Changed bcd0b7025a1e
- 1mo ago First seen · 387 lines · 102 tokens per session scan A a5fd304f9b21
stripe is a skill published in the GitHub repository vercel-labs/emulate (1,947 stars, last pushed 2d ago), licensed Apache-2.0. It adds 102 tokens to every session and 2,861 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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