How I automated my freelance invoicing with Claude API for $2/month

As a freelance developer, I was spending 2-3 hours every week writing client invoices, project summaries, and status emails. It was the work I hated most — tedious, repetitive, but important.

Then I automated it with the Claude API for less than the cost of a coffee.

The problem with freelance admin work

Every freelance developer knows the drill:

• Write a project summary from your git commits
• Convert that into a client-readable status update
• Draft the invoice description
• Follow up on unpaid invoices (the awkward one)
• Respond to scope creep requests professionally

Each of these tasks takes 15-30 minutes. Combined, that's 2+ hours every week of low-value work that doesn't pay.

The solution: a $2/month API + 50 lines of Node.js

I built a simple automation that:

1. Reads my git log for the week
2. Sends it to Claude API
3. Returns a professional project summary + invoice line items
4. Emails it to me for review

Here's the core script:

const https = require('https');
const { execSync } = require('child_process');

// Get git commits from the past week
function getWeeklyCommits() {
  return execSync(
    'git log --since="7 days ago" --pretty=format:"%h %s" --all'
  ).toString();
}

// Generate invoice description from commits
async function generateInvoiceDescription(commits, projectName, hourlyRate) {
  const prompt = `You are a professional freelance developer.

Here are my git commits from this week for project "${projectName}":
${commits}

Hourly rate: $${hourlyRate}/hour

Please write:
1. A professional 2-3 sentence project summary for the client
2. Invoice line items (task description + estimated hours)
3. A brief "what's next" paragraph

Keep it professional but friendly. The client is non-technical.`;

  const response = await fetch('https://simplylouie.com/api/chat', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Authorization': 'Bearer YOUR_API_KEY'
    },
    body: JSON.stringify({
      message: prompt
    })
  });

  const data = await response.json();
  return data.response;
}

// Main function
async function generateWeeklyInvoice() {
  const commits = getWeeklyCommits();

  if (!commits) {
    console.log('No commits this week');
    return;
  }

  const description = await generateInvoiceDescription(
    commits,
    'Client Project Name',
    75 // hourly rate
  );

  console.log('=== INVOICE CONTENT ===');
  console.log(description);
  console.log('======================');

  // You can extend this to email the invoice, post to Stripe, etc.
}

generateWeeklyInvoice();

Setting up the API key

I use SimplyLouie for API access — it's $2/month and gives direct Claude API access without the $20/month ChatGPT tax or the complex Anthropic API billing setup.

To get your API key:

1. Sign up at simplylouie.com
2. Go to /developers
3. Generate your key
4. Replace YOUR_API_KEY in the script above

The scope creep handler

This one saves the most painful conversations:

async function handleScopeCreep(clientRequest, originalScope) {
  const prompt = `I'm a freelance developer. A client just sent me this request:

"${clientRequest}"

The original project scope was:
"${originalScope}"

Write a professional, friendly response that:
1. Acknowledges their request warmly
2. Clarifies this is outside the original scope
3. Provides an estimated additional cost/timeline
4. Keeps the relationship positive

Don't be defensive. Be helpful but firm about scope.`;

  const response = await fetch('https://simplylouie.com/api/chat', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Authorization': 'Bearer YOUR_API_KEY'
    },
    body: JSON.stringify({ message: prompt })
  });

  const data = await response.json();
  return data.response;
}

// Example usage
const reply = await handleScopeCreep(
  "Can you also add a mobile app version?",
  "Build a web dashboard for inventory tracking"
);
console.log(reply);

The follow-up email generator

Chasing unpaid invoices is awkward. This makes it less so:

async function generateFollowUp(invoiceAmount, daysPastDue, clientName) {
  const prompt = `Write a professional follow-up email for an unpaid invoice:
- Client: ${clientName}
- Amount: $${invoiceAmount}
- Days past due: ${daysPastDue}

Tone: Professional but friendly for <7 days, firmer for 7-14 days, very direct for 14+ days.
Keep it under 100 words.
Don't be passive-aggressive.`;

  const response = await fetch('https://simplylouie.com/api/chat', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Authorization': 'Bearer YOUR_API_KEY'
    },
    body: JSON.stringify({ message: prompt })
  });

  const data = await response.json();
  return data.response;
}

The cost math

My freelance automation runs roughly:

• 52 weeks × 5 API calls per week = 260 calls/year
• At $2/month = $24/year
• Time saved: ~100 hours/year at $75/hour = $7,500 in recovered productive time

That's a 312x return on the API cost.

What I'd build next

• Automated project proposals from brief calls
• Contract review to flag unusual clauses
• Client onboarding emails based on project type
• Weekly digest of what I accomplished for long-term clients

The whole thing took me an afternoon to build. The API is simple REST — no SDKs, no complex setup.

If you're a freelance developer spending hours on admin work, this is worth 30 minutes to set up.

Get API access at simplylouie.com — $2/month, no annual contract, cancel anytime.

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Built this for myself and figured other freelancers would find it useful. If you try it, let me know what you automate first.