I Built a CBT Thought Journal in 50 Lines of Python

Last week I caught myself thinking: "I always mess everything up."

My therapist would recognize this as overgeneralization — a cognitive distortion where one mistake becomes "everything." But I didn't want to wait for my next session to check. So I built a journal that flags distortions automatically, using a free API I deployed myself.

Here's the whole thing in 50 lines.

The API: CBT Thought Analyzer

I deployed a CBT (Cognitive Behavioral Therapy) thought analyzer as a free API. It detects:

• 11 cognitive distortions (catastrophizing, all-or-nothing, overgeneralization, mind reading, fortune telling, should statements, labeling, personalization, etc.)
• 8 procrastination patterns (perfectionism block, fear of failure, task overwhelm, etc.)
• 4 attachment styles (Secure, Preoccupied, Fearful, Dismissing)

No AI model needed — it uses evidence-based keyword pattern matching for instant analysis. Based on David Burns' Feeling Good framework.

Endpoint: https://cbt-thought-analyzer.onrender.com

The Journal: 50 Lines of Python

import requests
from datetime import datetime
import json

BASE_URL = "https://cbt-thought-analyzer.onrender.com"

def analyze_thought(thought: str) -> dict:
    """Send a thought to the CBT analyzer and get distortions back."""
    resp = requests.post(f"{BASE_URL}/analyze", json={"text": thought}, timeout=30)
    resp.raise_for_status()
    return resp.json()

def check_procrastination(description: str) -> dict:
    """Check which procrastination patterns are keeping you stuck."""
    resp = requests.post(f"{BASE_URL}/procrastination", json={"text": description}, timeout=30)
    resp.raise_for_status()
    return resp.json()

def journal_entry(thought: str) -> None:
    """Write a journal entry with automatic CBT analysis."""
    timestamp = datetime.now().strftime("%Y-%m-%d %H:%M")

    print(f"
📝 {timestamp}")
    print(f"Thought: "{thought}"
")

    # Analyze for cognitive distortions
    result = analyze_thought(thought)
    distortions = result.get("distortions", [])

    if distortions:
        print("🔍 Detected distortions:")
        for d in distortions:
            print(f"  • {d['name']} (confidence: {d['confidence']}%)")
            print(f"    → {d['reframe']}")
    else:
        print("✅ No distortions detected — this thought looks balanced.")

    # Check for procrastination patterns
    proc = check_procrastination(thought)
    patterns = proc.get("patterns", [])

    if patterns:
        print("
⏰ Procrastination patterns:")
        for p in patterns:
            print(f"  • {p['name']}: {p['intervention']}")

# --- Daily Journal ---
thoughts = [
    "I always mess everything up.",
    "I can't start this project until I have the perfect plan.",
    "If I fail this presentation, my career is over.",
]

for thought in thoughts:
    journal_entry(thought)
    print("-" * 50)

How It Works

The API uses keyword pattern matching — no AI model, no API key needed for the free tier. Each distortion has a set of linguistic markers:

• Overgeneralization: "always", "never", "every time", "nobody"
• Catastrophizing: "if...then disaster", "what if...terrible"
• Should statements: "should", "must", "have to", "can't until"
• Mind reading: "they think", "everyone knows", "he probably"

When you send a thought, the API matches it against these patterns and returns the distortion name, a confidence score (based on how many markers matched), and a reframe prompt — a question that helps you challenge the distortion.

Why This Is Better Than a Chatbot

1. Instant — no waiting for an LLM to generate a response
2. Transparent — you can see exactly which keywords triggered the detection
3. Free — no API costs, no rate limits on the free tier
4. Private — your thoughts aren't sent to an AI company's servers
5. Evidence-based — the patterns come from David Burns' Feeling Good, not a model's guess

Try It Yourself

# Test the API with curl
curl -X POST https://cbt-thought-analyzer.onrender.com/analyze   -H "Content-Type: application/json"   -d '{"text": "I always fail at everything."}'

# Or with Python
pip install requests
python -c "
import requests
r = requests.post('https://cbt-thought-analyzer.onrender.com/analyze', json={'text': 'I always fail at everything.'})
print(r.json())
"

The API Is on RapidAPI

The API is now listed on RapidAPI — you can subscribe with a single click, get an API key, and use it in any language. There's also a Python SDK and JavaScript SDK in the GitHub repo.

The API is open and free to use right now. If you build something with it, let me know in the comments — I'd love to see what you create.

---

This is part of a CBT toolkit — 24 free mental health tools, all open source. Not a replacement for therapy.