Ninja Stealth API v1

AI Humanizer API

Our AI Humanizer API transforms AI-generated drafts into natural, human-grade writing inside your software applications. Lightweight REST architecture with X-API-Key authentication and real-time quota tracking. Starting at $0.12 per 1K words.

const response = await fetch("https://api.ninjahumanizer.com/v1/humanize", {
  method: "POST",
  headers: { 
    "X-API-Key": "nhk_live_9f82...",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({ text: "AI generated draft...", tone: "standard" })
});
const data = await response.json();
// data => { success: true, humanized_text: "Natural flow...", quota: { ... } }
200 OK | ~1.2s execution POST /v1/humanize

How It Works

Go from raw AI output to natural, human-quality text in three simple API calls.

1

Get Your API Key

Sign up, choose a plan, and generate your nhk_live_ API key from the developer dashboard in seconds.

2

Send Your AI Text

POST your AI-generated content to /v1/humanize with your preferred tone. That's one HTTP call.

3

Get Human-Quality Output

Receive naturally rewritten text that bypasses AI detectors like GPTZero, Turnitin, and Originality - ready to publish.

Transparent Developer Pricing Built for Scale

Predictable monthly word allowances with zero hidden charges. Upgrade, downgrade, or top up whenever your workload grows.

Standard

$24 /month

~$0.16 per 1K words

  • 150,000 words / month
  • 2,000 words / call
  • 60 requests / minute
  • Up to 2 API keys
Get Started
Recommended

Premium

$59 /month

~$0.12 per 1K words

  • 500,000 words / month
  • 4,000 words / call
  • 120 requests / minute
  • Up to 5 API keys
Get Started

Enterprise

Custom

High volume & custom SLAs

  • Multi-million monthly word volume
  • Tailored throughput & rate limits
  • Dedicated Slack channel & priority SLA
  • Flexible invoicing & security terms
Contact Sales

Running high on volume?

Purchase non-expiring top-up word packs anytime. Top-up words seamlessly extend your monthly plan allowance.

125,000 words $25/pack
Ninja Rewriting Engine

Natural Readability & Stealth Transformation

Our engine transforms AI-generated drafts into naturally phrased writing, helping your content read human while preserving your original context, technical terms, and structure.

POST /v1/humanize
200 OK
Input Payload AI Pattern Detected

"AI tools utilize predictive algorithms to generate structured sentences..."

Ninja Neural Transformation
Humanized Result Stealth Pass

"Our system transforms written content naturally to match authentic human expression..."

Bypasses Detectors: GPTZero • Turnitin • Originality
Feature Standard Plan Premium Plan
Included words / month 150,000 500,000
Words per request limit 2,000 4,000
Rate limits 60 req/min 120 req/min
API keys per account Up to 2 Up to 5
AI Detection Endpoint (/v1/detect)
Writing tones (/v1/tones) Standard tone All Pro & Premium tones
All 40+ languages supported

Why Developers Choose Our API

Purpose-built for production workloads - not a wrapper around generic LLMs.

Sub-2s Response Times

Optimized inference pipeline delivers humanized output in under 2 seconds - fast enough for real-time user-facing workflows.

Bypasses All Major Detectors

Consistently passes GPTZero, Turnitin, Originality.ai, Copyleaks, and ZeroGPT - tested continuously against the latest detection models.

40+ Languages Auto-Detected

No language parameter needed. Send text in English, Spanish, French, German, Japanese, Arabic, or any of 40+ supported languages - detected automatically.

Meaning & Context Preserved

Unlike generic paraphrasers, the engine preserves technical terms, proper nouns, data points, and original intent - no hallucinated rewrites.

Transparent Pay-Per-Word Billing

No surprise charges. Every response includes real-time quota usage so you always know exactly what you're spending.

Simple REST - No SDK Required

Standard JSON over HTTPS with X-API-Key auth. Works from any language, any stack - zero dependencies.

Who Uses the API

From solo developers to enterprise platforms - here's how teams integrate AI text humanization into their products.

SaaS Writing Platforms

Embed a "Humanize" button inside your AI writing tool, blog editor, or content management system. Your users get one-click humanization without leaving your product.

Content & SEO Agencies

Process hundreds of AI-drafted articles through your pipeline automatically. Ship bulk content that reads naturally and passes client-side AI detection checks.

EdTech & Academic Tools

Power study assistants, tutoring apps, and writing coaches that help students refine AI-assisted drafts into original, natural-sounding academic writing.

E-Commerce & Product Listings

Generate thousands of unique, human-sounding product descriptions at scale. Avoid duplicate content penalties and stand out in search results.

Email & Marketing Automation

Humanize AI-drafted email campaigns, newsletters, and ad copy before sending. Improve deliverability and engagement with authentic-sounding messaging.

Chatbots & AI Assistants

Post-process chatbot and virtual assistant responses so they sound conversational and human - not robotic. Ideal for customer support and sales workflows.

Built for Developers & Product Teams

Clean REST endpoints, deterministic JSON responses, and instant developer tooling.

Seamless Humanization

POST to /v1/humanize. Receives humanized text, word count metrics, active tone, and updated quota status in a single JSON payload.

Built-in AI Classifier

POST to /v1/detect to analyze text passages for AI probability score and human-likeness rating before or after rewriting.

Multi-Tone Selection

Call GET /v1/tones to retrieve active writing styles like standard, academic, creative, formal, or executive to match your product's voice.

Live Quota Diagnostics

Call GET /v1/status anytime to monitor per-minute rate limits, monthly words used, and remaining top-up pack balances.

Historical Usage Logs

Call GET /v1/usage to fetch a historical 30-day daily log of request volume, status codes, and word consumption.

Environment Keys & Security

Create up to 5 keys tagged for live or test environments. Revoke compromised keys instantly from your dashboard with zero downtime.

AI Humanizer API Integration Examples

Start using the AI Humanizer API in minutes. Authenticate requests by including your key in the X-API-Key header.

POST https://api.ninjahumanizer.com/v1/humanize
curl -X POST https://api.ninjahumanizer.com/v1/humanize \
  -H "X-API-Key: nhk_live_your_api_key_here" \
  -H "Content-Type: application/json" \
  -d '{
    "text": "Artificial intelligence is reshaping software creation...",
    "tone": "standard"
  }'

Frequently Asked Questions

Everything you need to know about billing, authentication, endpoints, and integration.

How does word-based billing work in Ninja Humanizer?

Each API plan includes a monthly word allowance. Words processed in requests are deducted from your active monthly plan quota first, then from any top-up word packs. Monthly plan allowances reset at every billing cycle.

What endpoints does the API expose?

The API provides POST /v1/humanize for text rewriting, POST /v1/detect for AI probability scoring, GET /v1/status for quota status, GET /v1/tones for available styles, and GET /v1/usage for 30-day analytics.

How do API keys and authentication work?

Every request must include your API key in the X-API-Key HTTP header. Keys start with nhk_live_ for production or nhk_test_ for testing. You can create up to 5 keys in your dashboard.

Which languages does the API support?

More than 40 languages including English, Spanish, French, German, Portuguese, Italian, Chinese, Japanese, Korean, Arabic, and more. Language is auto-detected automatically.

What happens if I exhaust my API word quota?

If your quota runs out, requests return a 429 quota_exhausted response. You can purchase top-up word packs anytime from your dashboard to restore access instantly.

Can I monitor remaining word quota programmatically?

Yes! Every successful response from /v1/humanize and /v1/detect returns a quota object with remaining words. You can also call GET /v1/status anytime.

Ready to Power Your App with Stealth Humanization?

Get started in minutes with simple REST endpoints, transparent pricing, and instant API keys.

NinjaHumanizer

Language / Idioma