Developer API

Humanizer API

Humanize AI-generated text at scale with one REST call. The same engine behind ProofreaderPro's humanizer, available for your own product. JSON in, JSON out, 60+ languages.

Request API access View the example

POSThttps://proofreaderpro.ai/api/humanizer/v1/humanize

Quickstart

Send your text with an Authorization: Bearer header. The humanizer returns the rewritten text as outputText.

curl https://proofreaderpro.ai/api/humanizer/v1/humanize \  -H "Authorization: Bearer YOUR_API_KEY" \  -H "Content-Type: application/json" \  -d '{    "text": "The results demonstrate a statistically significant effect...",    "writingMode": "Academic",    "intensityScalar": 0.5  }'

200 OKapplication/json

{  "outputText": "The findings point to a clear, statistically reliable effect...",  "metrics": { /* readability + length stats */ }}

60+ languages

Humanize text in English and 60+ other languages from the same endpoint, no separate models to wire up.

Writing modes + intensity

Choose Academic, Corporate, Creative or Blog/SEO, and dial the strength with a single intensity value.

One simple call

A single POST returns the rewritten text as JSON. Pass a requestId and retries are idempotent.

Endpoints

Authenticate every request with your API key as an Authorization: Bearer header.

POST/api/humanizer/v1/humanize

Rewrite AI text into natural, human-style prose.

GET/api/humanizer/v1/balance

Check remaining word credits for your key.

Text passes are validated for 50 to 1,000 words per request. Larger documents are split into multiple calls.

Pricing

Pay only for the words you send. Every request is billed per input word, and any request that fails is refunded to your balance automatically.

Starter

$28

100K words

$0.28 per 1,000 words

Growth

$125

500K words

$0.25 per 1,000 words

Pro

$440

2M words

$0.22 per 1,000 words

Best valueScale

$2,000

10M words

$0.20 per 1,000 words

Credits are valid for 12 months from purchase and work across all 60+ languages, every writing mode, and both English variants. Building something high volume, or want a white-label plan for your own product? Request access and we will tailor a rate to your usage.

Questions developers ask

What is the Humanizer API?

A REST endpoint that turns AI-generated text into natural human prose. Post your text, get the rewritten version back as JSON. It is the same humanizer that runs inside ProofreaderPro, opened up for your own product.

How do I get access?

Use the form below. Tell us who you are and what you are building, and we will send your API key and the full documentation, usually within one business day.

How much does it cost?

You buy word credits up front. Packs start at $28 for 100,000 words and the rate falls as the pack grows, down to $0.20 per thousand words on the largest one. No monthly fee.

What counts against my balance?

Only the words you send. The length of the rewrite that comes back makes no difference to the price.

Do I pay for a request that fails?

No. If a request does not produce a rewrite, its words are put back on your balance automatically.

How much text can one request hold?

Up to 1,000 words. Anything longer is split across several calls, which also keeps each response fast.

Request API access

Access is granted per project. Tell us what you're building and we'll send your API keys and full documentation.