How to Automatically Solve CAPTCHAs with NanoClaw and CapSolver

When your AI assistant browses the web inside a secure container, CAPTCHAs are still the number one obstacle. Protected pages block the agent, forms can't be submitted, and tasks stall out waiting for human intervention — even when the agent is sandboxed.

NanoClaw is a lightweight AI assistant framework that runs Claude agents in isolated Linux containers. Each agent gets its own filesystem, its own browser, and its own tools — completely separated from the host and from other agents. But like any browser automation, CAPTCHAs stop it cold.

CapSolver changes this completely. By loading the CapSolver Chrome extension into the container's Chromium browser, CAPTCHAs are solved automatically and invisibly in the background. No code. No API calls from your side. No changes to how you talk to your AI assistant.

The best part? You don't even need to mention CAPTCHAs to the AI. You just tell it to wait a moment before submitting — and by the time it clicks Submit, the CAPTCHA is already solved.

And because NanoClaw runs each agent in its own container, every agent gets its own isolated browser with its own CapSolver instance — no conflicts, no shared state, no interference between agents.

What is NanoClaw?

NanoClaw is a lightweight AI assistant framework designed for security and simplicity. It runs Claude agents in isolated Linux containers — giving each agent true OS-level isolation rather than application-level permission checks.

Key Features

• Container isolation: Every agent runs in its own Docker or Apple Container sandbox with an isolated filesystem
• Multi-channel messaging: Talk to your AI from WhatsApp, Telegram, Discord, Slack, and Gmail
• Built-in browser: Each container includes Chromium and the agent-browser tool for web automation
• Skills-based customization: Add capabilities through Claude Code skills — no config sprawl
• Minimal codebase: One process, a handful of files, easy to understand and customize
• Scheduled tasks: Set up recurring jobs that run Claude and message you the results

The Browser Inside the Container

Each NanoClaw container ships with Debian Chromium and the agent-browser CLI tool. The agent can:

• Open and navigate to any URL
• Read page content and take snapshots
• Click buttons, fill forms, select dropdowns
• Take screenshots
• Manage browser sessions

Think of it as giving each AI agent its own isolated browser window inside a locked-down sandbox.

What is CapSolver?

CapSolver is a leading CAPTCHA solving service that provides AI-powered solutions for bypassing various CAPTCHA challenges. With support for multiple CAPTCHA types and fast response times, CapSolver integrates seamlessly into automated workflows.

Supported CAPTCHA Types

• reCAPTCHA v2 (image-based & invisible)
• reCAPTCHA v3 & v3 Enterprise
• Cloudflare Turnstile
• Cloudflare 5-second Challenge
• AWS WAF CAPTCHA

Why This Integration is Different

Most CAPTCHA-solving integrations require you to write code — create API calls, poll for results, inject tokens into hidden form fields. That's how it works with tools like Crawlee, Puppeteer, or Playwright.

NanoClaw + CapSolver is fundamentally different:

The key insight: The CapSolver Chrome extension runs inside the container's Chromium browser. When the agent navigates to a page with a CAPTCHA, the extension detects it, solves it in the background, and injects the token — all before the agent even tries to submit the form.

You just need to give it time. Instead of telling the AI "solve the CAPTCHA", you simply say:

"Go to that page, wait 70 seconds, then click Submit."

That's it. The AI doesn't need to know about CapSolver at all.

The Container Advantage

Because NanoClaw runs each agent in its own container, you get a unique benefit: every agent has its own Chromium instance with its own CapSolver extension. This means:

• Multiple agents can solve CAPTCHAs simultaneously without conflicts
• Each agent's browser state is completely isolated
• No shared cookies, cache, or extension state between agents
• If one agent's browser crashes, others are unaffected

Prerequisites

Before setting up the integration, make sure you have:

1. NanoClaw installed and running (setup guide)
2. A CapSolver account with API key (sign up here)

No Chrome for Testing Required

Good news: NanoClaw containers use Debian Chromium (via apt-get install chromium), which is unbranded and fully supports the --load-extension flag. Unlike branded Google Chrome 137+, which silently removed extension loading support in mid-2025, Debian Chromium works out of the box.

You don't need to install Chrome for Testing, Playwright's bundled Chromium, or any alternative browser. The Chromium already in your container is all you need.

Step-by-Step Setup

Step 1: Download the CapSolver Chrome Extension

Download the CapSolver Chrome extension to your NanoClaw project directory:

1. Go to the CapSolver extension releases on GitHub
2. Download the latest CapSolver.Browser.Extension-chrome-vX.X.X.zip
3. Extract the zip:

mkdir -p assets/capsolver-extension
unzip CapSolver.Browser.Extension-chrome-v*.zip -d assets/capsolver-extension/

4. Verify the extraction worked:

ls assets/capsolver-extension/manifest.json

You should see manifest.json — this confirms the extension is in the right place.

Step 2: Set Your CapSolver API Key

Open the extension's config file at assets/capsolver-extension/assets/config.js and replace the apiKey value with your own:

export const defaultConfig = {
  apiKey: 'CAP-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX',  // ← your key here
  useCapsolver: true,
  // ... rest of config
};

You can get your API key from your CapSolver dashboard.

Step 3: Mount the Extension into the Container

NanoClaw runs agents in Docker containers. The extension directory needs to be available inside the container at /opt/capsolver-extension.

Option A: Auto-mount via container runner (recommended)

Place the extension at assets/capsolver-extension/ in your NanoClaw project directory. Then add a volume mount in src/container-runner.ts:

// Mount capsolver extension if present
const capsolverPath = path.join(process.cwd(), 'assets', 'capsolver-extension');
if (fs.existsSync(capsolverPath)) {
  mounts.push({
    hostPath: capsolverPath,
    containerPath: '/opt/capsolver-extension',
    readonly: true,
  });
}

Option B: Bake into the container image

Add to your container/Dockerfile:

# Add CapSolver extension
COPY ../assets/capsolver-extension/ /opt/capsolver-extension/

Then rebuild the container image.

Step 4: Configure agent-browser to Load the Extension

NanoClaw uses the agent-browser CLI tool for browser automation inside containers. It supports loading Chrome extensions via environment variables.

Add these environment variables to the container in src/container-runner.ts:

if (fs.existsSync(capsolverPath)) {
  args.push('-e', 'AGENT_BROWSER_EXTENSIONS=/opt/capsolver-extension');
  args.push('-e', 'DISPLAY=:99');
  args.push('-e', 'AGENT_BROWSER_ARGS=--no-sandbox,--disable-gpu,--disable-blink-features=AutomationControlled,--disable-background-timer-throttling');
  args.push('-e', 'AGENT_BROWSER_HEADED=true');
}

Step 5: Set Up Xvfb in the Container

Chrome extensions require a display, even in containers. Add xvfb to your container/Dockerfile and auto-start it in the entrypoint:

# Add xvfb to the apt-get install list
RUN apt-get update && apt-get install -y \
    chromium \
    xvfb \
    # ... other dependencies
    && rm -rf /var/lib/apt/lists/*

# Make Xvfb runnable by non-root user
RUN chmod u+s /usr/bin/Xvfb

# Create session directory (agent-browser needs this)
RUN mkdir -p /home/node/.claude/session-env && chown -R node:node /home/node/.claude

Update the entrypoint to start Xvfb automatically:

#!/bin/bash
set -e
# Start Xvfb for browser extensions
if [ -n "$DISPLAY" ]; then
  Xvfb $DISPLAY -screen 0 1280x720x24 &
  sleep 0.5
fi
# ... rest of entrypoint

Step 6: Restart NanoClaw

# Restart NanoClaw to pick up the changes
npm run dev
# or if running as a service:
pm2 restart nanoclaw

Step 7: Verify the Setup

Send a test message to your NanoClaw agent via any connected channel (Discord, WhatsApp, Telegram):

Go to https://www.google.com/recaptcha/api2/demo, wait 70 seconds,
then click Submit and tell me what text appears on the page.

If CapSolver is working, the agent should report: "Verification Success... Hooray!"

How to Use It

This is the most important section. Once setup is complete, using CapSolver with NanoClaw is dead simple.

The Golden Rule

Don't mention CAPTCHAs or CapSolver to the AI. Just give it time before submitting forms.

The AI agent doesn't need to know about CAPTCHAs. The extension handles everything in the background. All you need to do is include a wait time in your instructions so the extension has time to solve the challenge before the form is submitted.

Example 1: reCAPTCHA Demo

Send this to your NanoClaw agent (via Discord, WhatsApp, Telegram, or any channel):

Go to https://example.com, wait 70 seconds,
then click Submit and tell me what text appears on the page.

What happens behind the scenes:

1. The agent's container receives the message
2. The agent launches Chromium (with CapSolver extension loaded)
3. Chromium navigates to the page
4. CapSolver's content script detects the reCAPTCHA widget
5. The extension calls the CapSolver API and solves the challenge (usually within 10-20 seconds)
6. The token is injected into the hidden form field
7. After 70 seconds, the agent clicks Submit
8. The page shows: "Verification Success... Hooray!"

Example 2: Login to a Protected Site

Go to https://example.com/login, fill in the email field with
"[email protected]" and the password with "mypassword123",
then wait 30 seconds and click the Sign In button.
Tell me what page loads after signing in.

Example 3: Submit a Form Behind Turnstile

Open https://example.com/contact, fill in the contact form:
- Name: "John Doe"
- Email: "[email protected]"
- Message: "Hello, I have a question about your services."
Wait 45 seconds, then click Send Message. What confirmation appears?

Recommended Wait Times

Tip: When in doubt, use 70 seconds. It's better to wait a bit longer than to submit too early. The extra wait doesn't affect the result. In our testing, 60 seconds was borderline for reCAPTCHA v2 — 70 seconds worked reliably.

Natural Language Patterns That Work

Here are proven phrasings you can use:

• "Go to [URL], wait 70 seconds, then submit the form"
• "Navigate to [URL], fill in [fields], wait 30 seconds, then click [button]"
• "Open [URL] and after about a minute, click Submit and tell me the result"
• "Visit [URL], wait a moment for the page to fully load, then submit"

What NOT to Say

Avoid these — they can confuse the AI or trigger refusals:

• "Wait for the CAPTCHA to be solved" (the AI doesn't know about CAPTCHAs)
• "Use CapSolver to solve the verification" (the AI can't control extensions)
• "Click the reCAPTCHA checkbox" (the extension handles this — clicking may interfere)

How It Works Under the Hood

For the technically curious, here's what happens when the CapSolver extension is loaded inside a NanoClaw container:

  Your message                    NanoClaw Server
  ───────────────────────────────────────────────────
  "go to page,          ──►  Message router receives message
   wait 60s, submit"         │
                              ▼
                         Container spawned for agent
                         ┌─────────────────────────────────┐
                         │  Isolated Docker Container       │
                         │                                  │
                         │  Claude Agent (via Agent SDK)    │
                         │       │                          │
                         │       ▼                          │
                         │  agent-browser: navigate to URL  │
                         │       │                          │
                         │       ▼                          │
                         │  Chromium + CapSolver Extension  │
                         │  ┌───────────────────────────┐   │
                         │  │ Page with reCAPTCHA       │   │
                         │  │                           │   │
                         │  │ CapSolver Extension:      │   │
                         │  │ 1. Content script detects │   │
                         │  │    reCAPTCHA on the page  │   │
                         │  │ 2. Service worker calls   │   │
                         │  │    CapSolver API          │   │
                         │  │ 3. Token received         │   │
                         │  │ 4. Token injected into    │   │
                         │  │    hidden form field      │   │
                         │  └───────────────────────────┘   │
                         │       │                          │
                         │       ▼                          │
                         │  Agent waits 70 seconds...       │
                         │       │                          │
                         │       ▼                          │
                         │  agent-browser: click Submit     │
                         │       │                          │
                         │       ▼                          │
                         │  "Verification Success!"         │
                         └─────────────────────────────────┘
                              │
                              ▼
                         Response sent back via Discord/WhatsApp/etc.

How the Extension Loads

NanoClaw uses the agent-browser CLI tool, which supports loading Chrome extensions via the AGENT_BROWSER_EXTENSIONS environment variable. When this variable is set, agent-browser automatically passes --load-extension to Chromium.

1. Container starts with AGENT_BROWSER_EXTENSIONS=/opt/capsolver-extension set
2. Agent calls agent-browser open <url> — Chromium launches with the extension loaded
3. The extension activates — its service worker starts and content scripts are injected into every page
4. On pages with CAPTCHAs — the content script detects the widget, calls the CapSolver API, and injects the solution token into the page

Because NanoClaw uses Debian Chromium (not branded Google Chrome), the --load-extension flag works reliably without any workarounds. And because agent-browser handles the flag internally, you don't need to manage Chrome launch arguments yourself.

Troubleshooting

Extension Not Loading

Symptom: The agent navigates and submits but CAPTCHAs are not solved.

Possible causes:

1. Extension not mounted — Verify the volume mount is correct: ls /opt/capsolver-extension/manifest.json inside the container
2. AGENT_BROWSER_EXTENSIONS not set — Ensure the AGENT_BROWSER_EXTENSIONS env var is set to /opt/capsolver-extension in the container
3. Missing display — Chrome extensions need a display context. Make sure Xvfb is running with DISPLAY=:99

Browser Permission Error (session-env)

Symptom: Agent reports "can't create session directory at /home/node/.claude/session-env"

Cause: The agent-browser tool needs a writable session directory. If the host-mounted .claude directory doesn't contain it, the tool fails.

Fix: Ensure the directory exists in both the Dockerfile and on the host:

# In the Dockerfile:
RUN mkdir -p /home/node/.claude/session-env && chown -R node:node /home/node/.claude

# On the host (for the mounted volume):
mkdir -p data/sessions/main/.claude/session-env
chmod -R 777 data/sessions/main/.claude

CAPTCHA Not Solved (Form Fails)

Possible causes:

1. Not enough wait time — Increase to 70 seconds
2. Invalid API key — Check your CapSolver dashboard
3. Insufficient balance — Top up your CapSolver account
4. Extension not loaded — See "Extension Not Loading" above

Display Issues in Containers

Symptom: Chromium crashes or extensions don't work inside the container.

Fix: Ensure Xvfb is running before Chromium starts:

Xvfb :99 -screen 0 1280x720x24 &
export DISPLAY=:99

Add these to the container's entrypoint script so they run automatically.

Alternative: CapSolver Skills (API-Based Solving)

In addition to the Chrome extension approach, NanoClaw supports a second integration method using CapSolver Skills — a Python CLI tool that solves CAPTCHAs via the CapSolver API directly.

How It Works

Instead of the extension solving CAPTCHAs invisibly in the background, the agent explicitly:

1. Extracts the CAPTCHA site key from the page
2. Calls the CapSolver API via python3 /opt/capsolver-skills/scripts/solver.py
3. Receives a solution token
4. Injects the token into the page's hidden form field
5. Submits the form

Setup

Clone the capsolver-skills repo into your NanoClaw project:

git clone https://github.com/capsolver/capsolver-skills.git assets/capsolver-skills

Add python3 and dependencies to your container/Dockerfile:

RUN apt-get update && apt-get install -y python3 python3-pip \
    && pip3 install --break-system-packages requests python-dotenv

Mount the skills directory and pass the API key in src/container-runner.ts:

// Mount capsolver-skills
const capsolverSkillsPath = path.join(process.cwd(), 'assets', 'capsolver-skills');
if (fs.existsSync(capsolverSkillsPath)) {
  mounts.push({
    hostPath: capsolverSkillsPath,
    containerPath: '/opt/capsolver-skills',
    readonly: true,
  });
}

// Pass API key
args.push('-e', `API_KEY=${capsolverApiKey}`);

Set CAPSOLVER_API_KEY in your .env file:

CAPSOLVER_API_KEY=CAP-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Usage Example

@OpenCrawl Go to https://www.google.com/recaptcha/api2/demo,
use the capsolver skill to solve the reCAPTCHA,
then click Submit and tell me the result.

Supported CAPTCHA Types

The CapSolver Skills solver supports all major CAPTCHA types via CLI:

Extension vs Skills: When to Use Each

Tip: You can use both methods simultaneously. The extension handles CAPTCHAs automatically in the background, while the Skills solver gives the agent explicit control when needed.

Best Practices

1. Always Use Generous Wait Times

More wait time is always safer. The CAPTCHA is usually solved in 10-30 seconds, but network latency, complex challenges, or retries can add time. 60-70 seconds is the sweet spot.

2. Keep Your Messages Natural

Instead of:

"Navigate to URL, wait for captcha solver, then submit"

Use:

"Go to URL, wait about a minute, then submit the form"

Natural phrasing works better with the AI and avoids triggering safety refusals.

3. Monitor Your CapSolver Balance

Each CAPTCHA solve costs credits. Check your balance at capsolver.com/dashboard regularly to avoid interruptions.

4. Use the Volume Mount Approach

Volume mounting the extension (rather than baking it into the image) makes it easy to update the extension without rebuilding your container image. Just download the new version and restart NanoClaw.

Conclusion

The NanoClaw + CapSolver integration brings CAPTCHA solving to containerized AI agents — two ways:

1. Chrome Extension (zero-code): Mount the extension, set your API key, and CAPTCHAs are solved invisibly in the background. Just tell your AI to wait before submitting.
2. CapSolver Skills (API-based): The agent explicitly calls the CapSolver API to generate tokens and inject them into the page. More control, no waiting needed.

Both approaches are verified and working. Use the extension for simple "browse and submit" workflows, and CapSolver Skills when you need fine-grained control.

And thanks to NanoClaw's container architecture, every agent gets its own isolated browser and CapSolver instance — no conflicts, no shared state, true multi-agent CAPTCHA solving.

This is what CAPTCHA solving looks like when you have a containerized AI assistant: invisible, automatic, isolated, and zero-code.

Ready to get started? Sign up for CapSolver and use bonus code NANOCLAW for an extra 6% bonus on your first recharge!

FAQ

Do I need to tell the AI about CapSolver?

No. In fact, you should avoid mentioning CAPTCHAs or CapSolver in your messages. The extension works invisibly in the background. Just include a wait time in your instructions (e.g., "wait 70 seconds, then submit") to give the extension time to solve any CAPTCHAs on the page.

Why doesn't NanoClaw need Chrome for Testing?

NanoClaw containers use Debian Chromium installed via apt-get, which is unbranded. Unlike Google Chrome 137+ (which silently removed --load-extension support in mid-2025), Debian Chromium fully supports extension loading. No workarounds needed.

What CAPTCHA types does CapSolver support?

CapSolver supports reCAPTCHA v2 (checkbox and invisible), reCAPTCHA v3, Cloudflare Turnstile, AWS WAF CAPTCHA, and more. The Chrome extension automatically detects the CAPTCHA type and solves it accordingly.

How much does CapSolver cost?

CapSolver offers competitive pricing based on CAPTCHA type and volume. Visit capsolver.com for current pricing. Use bonus code NANOCLAW for an extra 6% on your first recharge.

Is NanoClaw free?

NanoClaw is open-source (MIT license) and free to run on your own hardware. You'll need an API key for the AI model — either an Anthropic API key directly, or an OpenRouter API key (which gives you access to Claude and other models through a single account). For CAPTCHA solving, you'll need a CapSolver account with credits.

How long should I tell the AI to wait?

For most CAPTCHAs, 60-70 seconds is sufficient. The actual solve time is usually 10-30 seconds, but adding extra buffer ensures reliability. When in doubt, use 70 seconds — in our testing, 60 seconds was borderline for reCAPTCHA v2.

How does container isolation help with CAPTCHA solving?

Each NanoClaw agent runs in its own Docker container with its own Chromium browser and CapSolver extension instance. This means multiple agents can solve CAPTCHAs simultaneously without conflicts — no shared cookies, no shared browser state, no interference. If one agent's browser session has issues, it doesn't affect any other agent.

Can I use this on a headless server?

Yes. You'll need Xvfb (X Virtual Framebuffer) for the display since Chrome extensions require a display context. Set DISPLAY=:99 and run Xvfb :99 in the background inside the container.