# Anthropic Claude Writing Watermark Checker (`rainminer/anthropic-claude-watermark-checker`) Actor

Paste text or upload PDF and DOCX to see if writing looks like Claude. Claude uses SynthID-Text with a private key — this Actor returns isAiGenerated as a classifier until a public detector exists. JSON includes confidence, likely source, and limitations. For editors and reviewers. No Claude login.

- **URL**: https://apify.com/rainminer/anthropic-claude-watermark-checker.md
- **Developed by:** [rainminer](https://apify.com/rainminer) (community)
- **Categories:** AI, Developer tools
- **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

from $5.00 / 1,000 text checkeds

This Actor is paid per event. You are not charged for the Apify platform usage, but only a fixed price for specific events.

Learn more: https://docs.apify.com/actors/running/actors-in-store.md#pay-per-event

## What's an Apify Actor?

Actors are web data automations that power AI and operations. They run on the Apify platform to scrape websites, process data, connect APIs, and automate workflows.
In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours,
and optionally produces a well-defined JSON output, datasets with results, or files in key-value store.
In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server.
Actors are written with capital "A".

## How to integrate an Actor?

If asked about integration, you help developers integrate Actors into their projects.
You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready.
The best way to integrate Actors is as follows.

- **AI agents and MCP clients** — the [Apify MCP server](https://docs.apify.com/integrations/mcp.md) at `https://mcp.apify.com` (remote, streamable HTTP, OAuth on first use).
- **Agentic workflows and local Actor development** — [Agent Skills](https://apify.com/.well-known/agent-skills/index.json) with the [Apify CLI](https://docs.apify.com/cli/docs.md): `npm install -g apify-cli`, then `apify login`.
- **JavaScript/TypeScript projects** — the official [JS/TS client](https://docs.apify.com/api/client/js/docs.md): `npm install apify-client`.
- **Python projects** — the official [Python client](https://docs.apify.com/api/client/python/docs.md): `pip install apify-client`.
- **Any other language** — the [REST API](https://docs.apify.com/api/v2.md).

For usage examples, see the [API](#api) section below.

For more details, see Apify documentation as [Markdown index](https://docs.apify.com/llms.txt) and [Markdown full-text](https://docs.apify.com/llms-full.txt).

# README

## Anthropic Claude Watermark Checker

**Anthropic Claude Watermark Checker** takes pasted text or uploaded files and returns structured JSON on whether the writing is **AI generated**, with a focus on **Claude-style** copy. It uses a **SynthID-Text**-aware classifier and asks: *Is this AI generated?* The headline output field is `isAiGenerated`.

Claude’s text watermark is a version of Google DeepMind **SynthID-Text**, but it uses **Anthropic’s own key**. Anthropic has said a public detection API is coming; this Actor does **not** have that key. It is a **classifier** that still gives you structured JSON you can store, plus honest `limitations` on the row.

![Claude](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b0/Claude_AI_symbol.svg/200px-Claude_AI_symbol.svg.png)

***

### What is Anthropic Claude Watermark Checker?

Paste a passage or upload a PDF / Word / text file. The Actor extracts text locally, sends a capped sample to the detector, and returns one dataset row per item: `isAiGenerated`, confidence, likely source, rationale, and billed token units.

No Claude login. Files are converted to text **before** the check so a large binary cannot be billed as extra tokens.

***

### What can this Actor do?

- Check **pasted text** or **uploaded files** (PDF, DOCX, TXT, Markdown, HTML, JSON, CSV)
- Return **`isAiGenerated`** plus Claude-focused classifier fields in structured JSON
- Sample long files from the **start, middle, and end**
- Cap characters per item so a huge upload cannot silently burn tokens
- Charge **per check** and **per 1,000 input tokens** of the sample
- Export JSON, CSV, or Excel, or pull results via the Apify API

***

### Why screen text for Claude?

New Claude models (from August 2026) embed a SynthID-Text-style watermark, but **you cannot read it without Anthropic’s key**. Teams still need a **repeatable JSON label** for documents they already hold.

Typical jobs:

1. **Policy teams** — log likely-Claude drafts while waiting for Anthropic’s detector API
2. **Admissions integrity** — screen essays and personal statements
3. **Hiring take-homes** — flag fully generated writeups
4. **Research labeling** — tag corpora as likely Claude vs human
5. **Support QA** — inspect long agent replies
6. **SEO review** — catch undifferentiated generated articles
7. **Newsroom intake** — label freelance copy
8. **Education tools** — show confidence, not a red-card verdict
9. **Brand voice audits** — find Claude-shaped pages
10. **Legal extras** — attach a classifier score next to produced files
11. **Community moderation** — sample long posts
12. **Internal audits** — sample exported docs for Claude-heavy writing

***

### How to use Anthropic Claude Watermark Checker

1. Open the Actor in [Apify Console](https://console.apify.com/)
2. Paste **Text** / **Texts**, or upload **Files**
3. Keep **Max characters per item** at the default unless you know you need to send a longer sample
4. Click **Start**
5. Download the dataset or read it via the Apify API

#### Input example

```json
{
  "text": "Four score and seven years ago our fathers brought forth on this continent, a new nation...",
  "texts": [
    "In today's rapidly evolving digital landscape, it is important to note that leveraging synergistic paradigms..."
  ],
  "files": ["https://example.com/memo.docx"],
  "maxItems": 5,
  "maxCharsPerItem": 24000
}
```

| Field | Type | Default | Description |
| --- | --- | --- | --- |
| `text` | string | — | One pasted passage |
| `texts` | string\[] | — | Extra pasted passages |
| `files` | string\[] | — | Uploaded file URLs (PDF, DOCX, or text) |
| `maxItems` | integer | `5` | Cap on pasted samples + files this run |
| `maxCharsPerItem` | integer | `24000` | Max characters sent to the detector per item (hard max 100,000) |

***

### Output

Each dataset item is one check. The headline field is **`isAiGenerated`**. `model` is the detector family (`synthid-text`), not a specific chat model.

```json
{
  "id": "a1b2c3d4e5f67890",
  "sourceType": "text",
  "sourceName": "pasted-text-1",
  "sourceUrl": null,
  "textPreview": "Four score and seven years ago...",
  "textLength": 312,
  "wordCount": 58,
  "truncated": false,
  "isAiGenerated": false,
  "watermarkDetected": null,
  "watermarkType": null,
  "matchesTargetProvider": false,
  "likelySource": "human",
  "likelihood": "low",
  "confidence": 0.64,
  "detectionMethod": "classifier",
  "rationale": "Well-known human speech; no access to Anthropic's SynthID-Text key.",
  "limitations": "Claude watermarks use Anthropic's key. This run is a writing-style classifier.",
  "inputTokens": 940,
  "outputTokens": 175,
  "billedTokenUnits": 1,
  "model": "synthid-text",
  "targetProvider": "anthropic-claude",
  "error": null,
  "checkedAt": "2026-08-26T12:00:00.000Z"
}
```

***

### Pricing

Long files use more tokens than a tweet. This Actor **passes that cost through with a margin**.

| Event | When | Price (FREE) |
| --- | --- | --- |
| `text-checked` | Once per successful analysis | **$0.005** |
| `input-1k-tokens` | Per **1,000 input tokens** of the sample actually sent (rounded up) | **$0.001** |
| Actor start | Per run (× memory GB) | platform default |

Failed downloads are **not** billed.

**Examples (excluding start fee):**

- \~500-word paste (~800 tokens) → ≈ **$0.006**
- 24,000-character file sample → ≈ **$0.012**

Leave `maxCharsPerItem` at 24,000 unless you have a reason to send more.

***

### Files and token safety

- Text is **extracted locally**. Images, audio, and zip archives are rejected.
- Files over **15 MB** are rejected.
- Longer documents are **sampled** up to `maxCharsPerItem`.
- Short samples (under ~50 words) are weak evidence.

For a **Google SynthID-Text** check, use [Google Gemini Watermark Checker](https://apify.com/rainminer/google-gemini-watermark-checker). For ChatGPT **images and audio** (the media OpenAI actually watermarks), use [OpenAI ChatGPT Watermark Checker](https://apify.com/rainminer/openai-chatgpt-watermark-checker).

***

### Is it legal to check AI-generated text?

This Actor only analyzes content **you provide**. It does not log into Claude. Do not treat the score as legal proof of authorship. A Claude watermark answers “was Claude involved?”, not who the user was.

***

### Tips

- Prefer **longer passages** — Anthropic notes watermark confidence rises with length
- Upload **text-based PDFs**, not scanned image-only pages
- Watch `billedTokenUnits` if a run costs more than you expected
- Start with `maxItems` 1–3 while you learn the output shape

***

### Image Credit

Image credit: [Anthropic](https://www.anthropic.com/)

# Actor input Schema

## `text` (type: `string`):

Paste one passage to check. Combine with Texts or Files to check several samples in one run.

## `texts` (type: `array`):

Additional pasted passages. Each item becomes one dataset row.

## `files` (type: `array`):

Upload documents to check. Text is extracted locally from PDF, DOCX, and plain-text files (.txt, .md, .html, .json, .csv) so the detector only sees the writing — not the raw file. Each file is one check. Large files are sampled (start, middle, end) up to Max characters per item.

## `maxItems` (type: `integer`):

Maximum number of pasted samples plus files to analyze in this run. Extra inputs are skipped.

## `maxCharsPerItem` (type: `integer`):

Hard cap on characters sent to the detector for each sample. Longer files are sampled from the start, middle, and end. Keep this modest — you are billed per 1,000 input tokens. Maximum 100,000.

## Actor input object example

```json
{
  "text": "Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.",
  "texts": [
    "In today's rapidly evolving digital landscape, it is important to note that leveraging synergistic paradigms can unlock unprecedented value for stakeholders across the ecosystem."
  ],
  "maxItems": 5,
  "maxCharsPerItem": 24000
}
```

# Actor output Schema

## `overview` (type: `string`):

No description

# API

You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup.

## JavaScript example

```javascript
import { ApifyClient } from 'apify-client';

// Initialize the ApifyClient with your Apify API token
// Replace the '<YOUR_API_TOKEN>' with your token
const client = new ApifyClient({
    token: '<YOUR_API_TOKEN>',
});

// Prepare Actor input
const input = {
    "text": "Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.",
    "texts": [
        "In today's rapidly evolving digital landscape, it is important to note that leveraging synergistic paradigms can unlock unprecedented value for stakeholders across the ecosystem."
    ],
    "maxItems": 5,
    "maxCharsPerItem": 24000
};

// Run the Actor and wait for it to finish
const run = await client.actor("rainminer/anthropic-claude-watermark-checker").call(input);

// Fetch and print Actor results from the run's dataset (if any)
console.log('Results from dataset');
console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`);
const { items } = await client.dataset(run.defaultDatasetId).listItems();
items.forEach((item) => {
    console.dir(item);
});

// 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs

```

## Python example

```python
from apify_client import ApifyClient

# Initialize the ApifyClient with your Apify API token
# Replace '<YOUR_API_TOKEN>' with your token.
client = ApifyClient("<YOUR_API_TOKEN>")

# Prepare the Actor input
run_input = {
    "text": "Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.",
    "texts": ["In today's rapidly evolving digital landscape, it is important to note that leveraging synergistic paradigms can unlock unprecedented value for stakeholders across the ecosystem."],
    "maxItems": 5,
    "maxCharsPerItem": 24000,
}

# Run the Actor and wait for it to finish
run = client.actor("rainminer/anthropic-claude-watermark-checker").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print(f"💾 Check your data here: https://console.apify.com/storage/datasets/{run.default_dataset_id}")
for item in client.dataset(run.default_dataset_id).iterate_items():
    print(item)

# 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start

```

## CLI example

```bash
echo '{
  "text": "Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.",
  "texts": [
    "In today'\''s rapidly evolving digital landscape, it is important to note that leveraging synergistic paradigms can unlock unprecedented value for stakeholders across the ecosystem."
  ],
  "maxItems": 5,
  "maxCharsPerItem": 24000
}' |
apify call rainminer/anthropic-claude-watermark-checker --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,rainminer/anthropic-claude-watermark-checker"
        }
    }
}

```

The hosted server signs you in with OAuth on first connect, so no API token belongs in this config. Clients without OAuth support can send an `Authorization: Bearer <APIFY_API_TOKEN>` header instead, using a token from API & Integrations in Apify Console (https://console.apify.com/settings/integrations).

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/6WXRng9Mm5l2vefMh/builds/iWBFRrouid6sCqP3d/openapi.json