Sim Zero Mode

Q: What is a Claude Code skill and how does the Sim Zero Mode skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Sim Zero Mode is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Engineering · Sub-category: testing · Last updated: 2026-06-18

Use when building/testing an app or agent that depends on paid APIs or LLM calls and you must exercise plumbing/UI/harness without spend or real intelligence, for CI, demos, local dev. Activates on test without burning API budget, demo without live calls, or fakes/offline mode.

From the source SKILL.md

A whole-application mode where everything runs on fake data with NO real LLM/paid/external calls. The app still works end-to-end — it just knows nothing. Every screen renders, every flow completes, every agent step fires; only the intelligence and the spend are absent.

What this skill does

Sim Zero Mode is a community-contributed Claude Code skill in the testing sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/sim-zero-mode/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when building/testing an app or agent that depends on paid APIs or LLM calls and you must exercise plumbing/UI/harness without spend or real intelligence, for CI, demos, local dev. Activates on test without burning API budget, demo without live calls, or fakes/offline mode.

Who uses this skill

The Sim Zero Mode Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 119,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/sim-zero-mode
curl -L https://claudskills.com/skills/sim-zero-mode/SKILL.md \
  -o ~/.claude/skills/sim-zero-mode/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/sim-zero-mode/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/sim-zero-mode/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\sim-zero-mode\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Sim Zero Mode Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/sim-zero-mode/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the Sim Zero Mode skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the Sim Zero Mode skill?

Use Sim Zero Mode when your Claude Code task falls under the Engineering category — specifically in the testing area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Sim Zero Mode" or describe the task and let Claude pick). Browse related skills at /category/engineering/.

What is a Claude Code skill and how does the Sim Zero Mode skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Sim Zero Mode is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Source: https://github.com/selamy-labs/agent-skills/blob/HEAD/skills/sim-zero-mode/SKILL.md
License: MIT
Author: selamy-labs

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

selamy-labs. (2026). Sim Zero Mode [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/sim-zero-mode/

BibTeX

@misc{sim-zero-mode-2026,
  author    = {selamy-labs},
  title     = {Sim Zero Mode [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/sim-zero-mode/}
}

Embed this skill

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Badge

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Part of ClaudSkills — the open registry for Claude Skills & Claude Code Skills. · What's New · Install guide · About · llms.txt

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