REST API

Watermark Remover API

Remove invisible AI watermarks from text programmatically. One endpoint. All known watermark types detected. Built for developers who need clean AI text at scale.

Get API Access View Documentation

const response = await fetch(
  "https://api.gptwatermarkremover.com/v1/clean",
  {
    method: "POST",
    headers: {
      "X-API-Key": "YOUR_API_KEY",
      "Content-Type": "application/json"
    },
    body: JSON.stringify({ text: "Your AI-generated text here" })
  }
);

const { cleaned_text } = await response.json();

Built for Developers

A simple, reliable API that does one thing well

Fast Response

Sub-100ms response times. Process text instantly without blocking your application.

All Known Watermarks

Detect zero-width spaces, soft hyphens, bidirectional marks, and other hidden Unicode characters.

Simple Integration

Single endpoint, JSON in/out. Works with any language that can make HTTP requests.

No Text Storage

Your text is processed and immediately discarded. Nothing is logged or stored.

99.9% Uptime

Built on reliable infrastructure with automatic failover and global edge distribution.

100K Character Limit

Process documents up to 100,000 characters per request. Handle long-form content easily.

API Response

Send text in, get clean text back with usage tracking

POST/v1/clean

Request Body

{
  "text": "Your AI-generated text with hiddenwatermarks"
}

200application/json

Response

{
  "cleaned_text": "Your AI-generated text with hidden watermarks",
  "credits_used": 5,
  "credits_remaining": 995
}

cleaned_text

Your text with all watermarks removed

credits_used

Total API calls used this billing period

credits_remaining

API calls remaining until reset

Error Handling

The API uses standard HTTP status codes. Here's what to expect when things don't go as planned.

400Bad RequestInvalid request body or missing required fields.

{
  "error": "Missing or invalid \"text\" field in request body"
}

401UnauthorizedMissing or invalid API key.

{
  "error": "Missing API key. Include X-API-Key header."
}

403ForbiddenValid API key but no active subscription.

{
  "error": "Active subscription required to use the API"
}

429Too Many RequestsMonthly API credit limit exceeded.

{
  "error": "Monthly API credit limit exceeded",
  "used": 1000,
  "limit": 1000,
  "resets_at": "2024-02-01T00:00:00Z"
}

400Bad RequestText exceeds maximum length.

{
  "error": "Text exceeds maximum length of 100,000 characters",
  "length": 150000,
  "max_length": 100000
}

Handling Rate Limits

When you receive a 429 response, check the resets_at field to know when your credits refresh. Consider implementing exponential backoff or upgrading your plan for higher limits.

Retrying Failed Requests

For 5xx errors, implement retry logic with exponential backoff. Start with a 1-second delay and double it for each retry, up to a maximum of 3 attempts. Don't retry 4xx errors without fixing the request.

How It Works

Three simple steps to clean AI text programmatically

Generate API Key

Create your key in seconds from the dashboard

Send Text

POST your AI-generated text to our endpoint

Get Clean Text

Receive watermark-free text instantly

Watermark Types We Detect

Our API detects and removes all known invisible Unicode characters used by AI systems like ChatGPT, Claude, Gemini, and others to watermark generated text.

Zero-Width Characters

Invisible characters with no visual width, commonly inserted by AI systems to mark generated text.

Zero-Width Space

Most common AI watermark. Invisible space character inserted between words or characters.

Zero-Width Non-Joiner

Prevents character joining in scripts like Arabic. Used as hidden marker in AI text.

Zero-Width Joiner

Forces character joining. Commonly used in emoji sequences, exploited for watermarking.

Byte Order Mark

Originally for encoding detection. When embedded mid-text, serves as invisible watermark.

Word Joiner

Prevents line breaks. Invisible character used to mark AI-generated content.

Formatting Characters

Characters that affect text rendering or spacing without being visible.

Soft Hyphen

Marks where a word can break. Invisible unless line breaks at that point.

Combining Grapheme Joiner

Affects how characters combine. Used to invisibly mark text.

Function Application

Mathematical invisible operator. Repurposed as text watermark.

Invisible Times

Mathematical multiplication marker. Zero-width, used in watermarking.

Invisible Separator

Mathematical separator with no width. Hidden text marker.

Bidirectional Control

Characters that control text direction, often invisible and exploitable for watermarking.

Left-to-Right Mark

Forces left-to-right text direction. Invisible directional override.

Right-to-Left Mark

Forces right-to-left text direction. Hidden directional marker.

Directional Embeddings

Multiple characters that embed text direction. Invisible formatting controls.

Directional Overrides

Override text direction rendering. Hidden watermark characters.

Variation Selectors

Characters that modify how preceding characters render, often invisibly.

Standard Variation Selectors

Selectors that change character appearance. Often invisible modifications.

Extended Variation Selectors

Extended selectors for specialized use. Rarely used, suspicious when found in regular text.

Annotation Characters

Characters for interlinear annotations, invisible in most contexts.

Annotation Anchor

Marks annotation start. Invisible formatting character.

Annotation Separator

Separates annotation elements. Zero-width marker.

Annotation Terminator

Ends annotation. Hidden text marker.

Why Do AI Systems Add Watermarks?

Large language models like ChatGPT, Claude, and Gemini embed invisible watermarks to enable detection of AI-generated content. These watermarks use Unicode characters that have zero visual width but can be detected programmatically. Our API removes all known watermark patterns while preserving your text's meaning and formatting.