DEV Community: ming zhang

I Built a Free AI Detector + Humanizer with Sentence-Level Highlighting

ming zhang — Sat, 11 Apr 2026 14:43:13 +0000

The Problem

I got tired of pasting text into AI detection tools and getting a single percentage back. "83% AI-generated" — but which sentences? Without knowing what to fix, the number is useless.

So I built a tool that shows you exactly which sentences trigger AI detection, and optionally rewrites them.

What It Does

HumanizeAI — free, no signup, no login.

AI Detection — paste any text, get a sentence-by-sentence breakdown. Each sentence is highlighted: red = likely AI, green = likely human. You see a circular gauge with the overall score and individual detector ratings from 4 different detection algorithms.
Text Humanization — click "Humanize" and it rewrites the text to sound more natural. You can compare before/after side by side.

Technical Implementation

Stack

Next.js 16 (App Router)
Tailwind CSS v4 — the new CSS-first config, no more tailwind.config.js
AI text model via API — for text humanization
Custom detection engine — multi-detector scoring with weighted analysis
Cloudflare Pages — edge deployment via @opennextjs/cloudflare

Sentence-Level Highlighting

The detection endpoint (/api/detect) returns per-sentence results:

interface DetectionResult {
  sentence: string;
  aiProbability: number;    // 0-100
  detectors: {
    name: string;
    score: number;
    label: string;           // "AI" | "Human" | "Mixed"
  }[];
}

Each sentence gets a color based on its AI probability:

Red (>70%): likely AI-generated
Yellow (40-70%): uncertain
Green (<40%): likely human-written

Gauge Dashboard

Built with pure SVG — no chart library needed:

// Circular progress ring using SVG circle + stroke-dasharray
const circumference = 2 * Math.PI * radius;
const offset = circumference - (score / 100) * circumference;

The gauge color shifts dynamically: red → yellow → green based on the overall AI score.

Multi-Detector Scoring

Instead of relying on one detection method, the tool runs 4 independent detectors and aggregates the results. Each detector analyzes different patterns (perplexity, burstiness, vocabulary distribution, sentence structure). The final score is a weighted average displayed as individual progress bars.

Rate Limiting

Rate limited per IP with daily caps to prevent abuse. Simple in-memory implementation — no Redis needed at this scale.

Deployment on Cloudflare Pages

Deployed via @opennextjs/cloudflare adapter. The entire app runs on the edge — API routes and all. No separate backend server.

npm install @opennextjs/cloudflare
npx opennextjs-cloudflare build
npx wrangler pages deploy

Connected to GitHub for auto-deploys on push.

Design Decisions

Decision	Why
No signup/login	Friction kills conversion for simple tools
Sentence-level, not paragraph	Users need to know what to fix
Multi-detector	Single detectors have high false positive rates
SVG gauge, no library	Keeps bundle small (~0 dependency overhead)
In-memory rate limit	Simple, free, works at low traffic
Cloudflare Pages	Free tier is generous, edge = fast globally

Limitations (Honest Take)

AI humanization has a ceiling. Good prompting can reduce AI scores significantly, but eliminating them entirely is unreliable. The detection feature is the real value — humanization is a helper.
Rate limiting resets on deploy. Fine for now, not for scale.
No file upload or PDF export yet. On the backlog.

Try It

HumanizeAI — paste some text, see which sentences look AI-generated, optionally humanize. Free, no account needed.

Feedback welcome — what features would make this actually useful for your workflow?

How I Built ResumeAI: A Free Tool to Optimize Your Resume

ming zhang — Sat, 28 Mar 2026 01:58:25 +0000

Why I Built This

Job hunting is competitive. I noticed many candidates struggle with resume formatting, weak action verbs, and missing keywords. I wanted a simple tool that gives instant, actionable feedback.

What It Does

ResumeAI analyzes and optimizes your resume in seconds:

Paste your resume text
Get AI-powered improvement suggestions
See your score across 5 dimensions (clarity, impact, keywords, structure, achievements)
Download optimized version as PDF

Free to use, no signup required.

How It Works

Built with:

Next.js for the frontend
Tailwind CSS for styling
GLM-4 for resume analysis
Cloudflare Workers for edge deployment

The app evaluates resumes on 5 key dimensions, each scored out of 20, with specific suggestions for improvement.

Try It Out

ResumeAI - Free, no signup required

Feedback Welcome

What features would help you land more interviews?

How I Built HumanizeAI: A Free Tool to Make AI Text Sound Human

ming zhang — Thu, 26 Mar 2026 00:28:52 +0000

Why I Built This

As a content creator, I noticed AI detection tools were becoming stricter. Many genuine creators were getting flagged just for using AI assistance. I wanted a simple tool to help.

What It Does

HumanizeAI transforms AI-generated text into natural, human-like content:

Paste any AI text (ChatGPT, Claude, etc.)
Get humanized output instantly
Free to use, no signup required

How It Works

Built with:

Next.js for the frontend
Tailwind CSS for styling
GLM-4 for text transformation
Cloudflare Workers for edge deployment

The app uses a simple API route to process text through the AI model, with rate limiting to prevent abuse.

Try It Out

HumanizeAI - Free, no signup required

Feedback Welcome

I'd love to hear your thoughts and suggestions! What features would you find useful?