API Reference v1.1

AI Humanizer API Documentation

Humanize AI-generated text, detect AI authorship, and track usage through a simple REST API. Simple authentication, predictable pricing, 40+ languages.

Base URLhttps://api.finix-wh.earnwithdigital.online

Starting at$0.14/ 1K words

Watch Video Guide

Quickstart

Get up and running in under a minute.

1

Get your API key

Sign up or log in at finix-wh.earnwithdigital.online, purchase an API subscription, and create your key from the dashboard.

2

Make your first request

Install an official SDK, or call the REST API directly:

npm install @writehuman/sdkpip install writehuman

// npm install @writehuman/sdk
import { WriteHuman } from "@writehuman/sdk";

const wh = new WriteHuman({ apiKey: "wh_live_your_api_key_here" });
const out = await wh.humanize("Artificial intelligence has revolutionized the way we approach content creation and digital communication.");
console.log(out.results[0]);
console.log(out.words_remaining.total, "words left");

3

See the response

Standard plans return a single result. Premium plans return 3 variations with human-likeness scores.

{
  "id": "hum_a1b2c3d4e5f6",
  "created": 1778533901580,
  "results": [
    "AI has changed how we create content and communicate online."
  ],
  "scores": null,
  "input_words": 14,
  "words_remaining": {
    "included": 124986,
    "topup": 0,
    "total": 124986
  }
}

Video Guide

A step-by-step walkthrough of authentication and setup, followed by three real integrations: calling the API directly with Python, wiring it into a Lovable app, and using it with Claude.

Authentication

All API requests require a Bearer token in the Authorization header. You can create and manage API keys from your dashboard.

Authorization: Bearer wh_live_your_api_key_here

Keys use the prefix wh_live_ followed by a unique token. Keep your keys secret — treat them like passwords. You can create up to 5 keys and revoke any key at any time.

Plans & Limits

Choose a plan that fits your usage. All plans include monthly word allowances that reset each billing cycle.

	Standard	Premium
Monthly words	125,000	400,000 – 3,000,000
Max words per request	2,000	4,000 – 6,000
Output variations	1	3
Human-likeness scores
Rate limit	40 req/min	120 – 160 req/min

Standard

Monthly words125,000

Max words per request2,000

Output variations1

Human-likeness scores

Rate limit40 req/min

Premium

Monthly words400,000 – 3,000,000

Max words per request4,000 – 6,000

Output variations3

Human-likeness scores

Rate limit120 – 160 req/min

Premium plans automatically return 3 output variations per request with human-likeness scores. Standard plans return a single result without scores. Usage is tracked by input-text word count. Words are deducted from your subscription first, then any top-up credits. Top-up packs (100,000 words each) never expire. Premium is available in four monthly word sizes: 400K, 800K, 1.5M, and 3M. Premium 400K allows 4,000 words per request and 120 requests per minute; 800K and up allow 6,000 and 160.

Errors

Every non-2xx response is a JSON object with a stable machine-readable code and a human-readable error message. Branch on code; the wording of error may change. A 402 for an exhausted balance also carries words_remaining. Every 429, 503 and 504 carries a Retry-After header in seconds; wait at least that long before retrying. Those statuses leave nothing charged and are safe to retry. A 429, 503 or 504 without the JSON body and code came from a load balancer or proxy, not the API, and carries no such guarantee: handle it like a client-side timeout and do not resend a billed request automatically. Words are charged only on a 200, with one exception: a 500 billing_failed is returned after a result was produced but the usage write failed part-way, and some of the request's words, from the included allowance and/or from top-up credits, may already have been charged. Check /v1/usage after one.

Status	`code`	Meaning
422	invalid_request	The body failed validation (missing `text`, too short or too long).
422	forbidden_param	A parameter that is not available on the public API was sent.
422	word_limit	The input is over the per-request word cap for your plan.
422	moderation_blocked	Content moderation refused the input (`/v1/humanize` only).
401	missing_api_key	No usable `Authorization: Bearer` header.
401	invalid_api_key	The key is unknown or revoked.
402	no_subscription	The key is valid but the account has no active API subscription.
402	insufficient_balance	Not enough words left for this request; `words_remaining` is included.
403	reverify_required	The account must be re-verified by email. The account owner signs in at finix-wh.earnwithdigital.online to continue; then the account's newest key created after the check began works within about a minute; every other key stays disabled until the check ends, so create a new key. Not retried by the SDKs.
429	rate_limited	Over your plan's requests per minute. `Retry-After` is the time to the next window.
429	auth_locked_out	Too many failed authentications from this address. `Retry-After` is the remaining lockout.
429	queue_full	The admission queue is full. Retry after `Retry-After`.
429	queue_timeout	The request waited in the admission queue past its deadline. Retry after `Retry-After`.
503	at_capacity	Cluster-wide capacity shed. Retry after `Retry-After`.
503	billing_unavailable	The billing store is unreachable; the request was refused rather than served unmetered. Retry after `Retry-After`.
503	detector_unavailable	The detector, or the translation step before it, is unavailable (`/v1/detect` only). Retry after `Retry-After`.
504	timeout	Generation did not finish within the server deadline (`/v1/humanize` only). Nothing charged; retry after `Retry-After`.
500	processing_failed	Generation raised an error.
500	no_results	Generation finished without a usable result.
500	safety_limit	Generation produced far more text than the input; discarded.
500	billing_failed	The result was produced but the usage write failed part-way; included and/or top-up words may already have been charged. Check `/v1/usage`.

Endpoint Reference

Three REST endpoints, one base URL, and one Bearer key. All requests authenticate the same way.

POST/v1/humanize

https://api.finix-wh.earnwithdigital.online/v1/humanize

Rewrite AI-generated text to sound naturally human. Deducts input words from your balance. Usage is tracked by input text word count. Words are deducted from your monthly subscription allowance first, then from any purchased top-up credits. The public API accepts text, tone, and language only — model, num_outputs, and sequence_id are not available.

Request Body — application/json

textrequired

string

The text to humanize.

>= 30 characters, <= 100,000 characters

toneoptional

string

Optional writing tone. Omit for default style.

Allowed: professional, academic, blog, casual, creative, scientific, technical

languageoptional

string | null

Target language (e.g. English, Spanish, Chinese (Mandarin)). Auto-detected if omitted.

200Text humanized successfully

Response Body — application/json

id

string

Unique identifier for this humanization request.

created

integer

Unix timestamp (milliseconds) when the request was received.

results

string[]

Humanized text variations, sorted by score (best first).

scores

(number | null)[] | null

Human-likeness score for each result (0–1, higher = more human).

Premium plans only. `null` on Standard plans.

input_words

integer

Number of words billed for this request.

words_remaining

object

Your remaining word balance after this request.

Fields: included (integer), topup (integer), total (integer)

Error Responses

401

Missing or invalid API key.

Invalid API key

{
  "error": "Invalid API key",
  "code": "invalid_api_key"
}

Missing Authorization header

{
  "error": "Missing or invalid Authorization header. Use: Bearer <api_key>",
  "code": "missing_api_key"
}

402

No active subscription or insufficient word balance.

No active subscription

{
  "error": "No active subscription",
  "code": "no_subscription"
}

Insufficient word balance

{
  "error": "Insufficient word balance",
  "code": "insufficient_balance",
  "words_remaining": {
    "included": 12,
    "topup": 0,
    "total": 12
  }
}

403

The account must be re-verified by email before its keys are served again (HTTP 403). The account owner signs in at finix-wh.earnwithdigital.online and follows the emailed link. The account's newest key created after the check began then works within about a minute; every other key stays disabled until the check ends, so create a new key on the dashboard. Nothing is charged. Do not retry automatically.

{
  "error": "This account must be re-verified by email. The account owner should sign in at finix-wh.earnwithdigital.online to continue.",
  "code": "reverify_required"
}

422

Invalid input, forbidden parameters, over word limit, or content blocked by moderation.

Invalid request body

{
  "error": "Invalid request: ...",
  "code": "invalid_request"
}

`model` is not available on the public API

{
  "error": "The model parameter is not available",
  "code": "forbidden_param"
}

`num_outputs` is not available on the public API

{
  "error": "The num_outputs parameter is not available",
  "code": "forbidden_param"
}

`sequence_id` is not available on the public API

{
  "error": "The sequence_id parameter is not available",
  "code": "forbidden_param"
}

Over word limit

{
  "error": "Input exceeds per-request limit of 2000 words for your plan. Received ~2500 words.",
  "code": "word_limit"
}

Content blocked

{
  "error": "Content blocked: sexual",
  "code": "moderation_blocked"
}

429

Rate limit, queue capacity, or too many failed auth attempts.

Rate limited

{
  "error": "Rate limit exceeded for your plan (api_standard -> 40/min). api_standard: 40/min | api_premium: 120/min | api_premium 800K+: 160/min",
  "code": "rate_limited"
}

Too many failed auth attempts

{
  "error": "Too many failed authentication attempts",
  "code": "auth_locked_out"
}

Request queue full

{
  "error": "Too many queued requests. Please retry shortly.",
  "code": "queue_full"
}

Queue wait timeout

{
  "error": "Request waited too long for capacity. Please retry.",
  "code": "queue_timeout"
}

500

Processing failure. No words charged, except that `billing_failed` may have charged some of the request's words (included and/or top-up) before the usage write failed.

Generation failed

{
  "error": "Processing failed",
  "code": "processing_failed"
}

Generation returned nothing usable

{
  "error": "Processing returned no results",
  "code": "no_results"
}

Output exceeded the safety limit

{
  "error": "Output exceeded safety limit",
  "code": "safety_limit"
}

Billing update failed after generation

{
  "error": "Billing update failed",
  "code": "billing_failed"
}

503

Service at capacity, or billing temporarily unavailable. No words charged.

Service at capacity

{
  "error": "Service is at capacity. Please retry shortly.",
  "code": "at_capacity"
}

Billing temporarily unavailable

{
  "error": "Service temporarily unavailable, please retry shortly.",
  "code": "billing_unavailable"
}

504

The request did not finish within the server deadline (170 seconds from request entry; generation is stopped once 10 seconds remain so that billing is never cut part-way). No words charged; safe to retry.

{
  "error": "Processing did not finish within 160 seconds. Nothing was charged; please retry.",
  "code": "timeout"
}

GET/v1/usage

https://api.finix-wh.earnwithdigital.online/v1/usage

Retrieve your current word usage, plan tier, and API version. Read-only — it never deducts words. Remaining balance = included_words − words_used_this_cycle + topup_balance.

200Usage returned

Response Body — application/json

included_words

integer

Words included in your plan each billing cycle.

words_used_this_cycle

integer

Words used so far in the current billing cycle.

topup_balance

integer

Remaining top-up words. Top-up packs never expire.

tier

string

Your plan: api_standard or api_premium.

version

string

Current API version.

{
  "included_words": 400000,
  "words_used_this_cycle": 18311,
  "topup_balance": 100000,
  "tier": "api_premium",
  "version": "v1.1"
}

Error Responses

401

Missing or invalid API key.

Invalid API key

{
  "error": "Invalid API key",
  "code": "invalid_api_key"
}

Missing Authorization header

{
  "error": "Missing or invalid Authorization header",
  "code": "missing_api_key"
}

402

No active subscription (HTTP 402).

{
  "error": "No active subscription",
  "code": "no_subscription"
}

403

The account must be re-verified by email before its keys are served again (HTTP 403). The account owner signs in at finix-wh.earnwithdigital.online and follows the emailed link. The account's newest key created after the check began then works within about a minute; every other key stays disabled until the check ends, so create a new key on the dashboard. Nothing is charged. Do not retry automatically.

{
  "error": "This account must be re-verified by email. The account owner should sign in at finix-wh.earnwithdigital.online to continue.",
  "code": "reverify_required"
}

429

Too many failed auth attempts.

{
  "error": "Too many failed authentication attempts",
  "code": "auth_locked_out"
}

POST/v1/detect

https://api.finix-wh.earnwithdigital.online/v1/detect

Score text for AI authorship using WriteHuman's detection model. Billed per input word (the original text), the same way as /v1/humanize. Non-English input is automatically translated to English before scoring. Set include_sentences to true for a per-sentence breakdown. Note: ai_probability runs 0–1 where 1 = AI — the opposite orientation of the humanize scores field.

Request Body — application/json

textrequired

string

The text to score for AI authorship.

>= 10 characters, <= 100,000 characters

languageoptional

string | null

Language of the text. Auto-detected if omitted; non-English text is translated to English before scoring.

include_sentencesoptional

boolean

Return a per-sentence AI-probability breakdown.

Default: false

200Text scored successfully

Response Body — application/json

scanId

string | null

Unique identifier for this detection scan.

version

string | null

Detector model version.

versionID

string | null

Detector build identifier.

ai_probability

number | null

Probability the text is AI-generated (0–1, where 1 = AI).

Opposite orientation from the /v1/humanize scores field, where higher = more human.

predicted_class

string | null

Overall label: ai, human, or mixed.

class_probabilities

object

Probability for each class.

Fields: ai, human, mixed

request_meta

object

Length of the scored text.

doc_length: { chars, tokens }

language

string

Detected (or supplied) language of the input.

sentences

array

Per-sentence breakdown, each { text, ai_prob }.

Present only when include_sentences is true.

{
  "scanId": "20260609OMIOISUZ",
  "version": "txtdetect-2026-05-14",
  "versionID": "V1.1.1",
  "ai_probability": 0.94,
  "predicted_class": "ai",
  "class_probabilities": { "ai": 0.94, "human": 0.04, "mixed": 0.02 },
  "request_meta": { "doc_length": { "chars": 642, "tokens": 98 } },
  "language": "English",
  "sentences": [
    { "text": "Artificial intelligence has rapidly transformed modern business.", "ai_prob": 0.97 },
    { "text": "Many teams now depend on it every single day.", "ai_prob": 0.61 }
  ]
}

Error Responses

401

Missing or invalid API key.

Invalid API key

{
  "error": "Invalid API key",
  "code": "invalid_api_key"
}

Missing Authorization header

{
  "error": "Missing or invalid Authorization header",
  "code": "missing_api_key"
}

402

No active subscription or insufficient word balance.

No active subscription

{
  "error": "No active subscription",
  "code": "no_subscription"
}

Insufficient word balance

{
  "error": "Insufficient word balance",
  "code": "insufficient_balance",
  "words_remaining": {
    "included": 12,
    "topup": 0,
    "total": 12
  }
}

403

The account must be re-verified by email before its keys are served again (HTTP 403). The account owner signs in at finix-wh.earnwithdigital.online and follows the emailed link. The account's newest key created after the check began then works within about a minute; every other key stays disabled until the check ends, so create a new key on the dashboard. Nothing is charged. Do not retry automatically.

{
  "error": "This account must be re-verified by email. The account owner should sign in at finix-wh.earnwithdigital.online to continue.",
  "code": "reverify_required"
}

422

Invalid input or over the per-request word limit.

Invalid request body

{
  "error": "Invalid request: ...",
  "code": "invalid_request"
}

Over word limit

{
  "error": "Input exceeds per-request limit of 2000 words for your plan. Received ~2500 words.",
  "code": "word_limit"
}

429

Rate limit or too many failed auth attempts.

Rate limited

{
  "error": "Rate limit exceeded for your plan (api_standard -> 40/min). api_standard: 40/min | api_premium: 120/min | api_premium 800K+: 160/min",
  "code": "rate_limited"
}

Too many failed auth attempts

{
  "error": "Too many failed authentication attempts",
  "code": "auth_locked_out"
}

500

Billing update failure after a successful scan. Some of the request's words (included and/or top-up) may already have been charged before the write failed.

{
  "error": "Billing update failed",
  "code": "billing_failed"
}

503

Detector unavailable or at capacity, translation failed, or billing temporarily unavailable. No words charged.

Detector unavailable, at capacity, or translation failed

{
  "error": "Detection service unavailable. Please retry.",
  "code": "detector_unavailable"
}

Billing temporarily unavailable

{
  "error": "Service temporarily unavailable, please retry shortly.",
  "code": "billing_unavailable"
}

Code Examples

Full working examples in popular languages. Replace the API key with your own to get started.

Official SDKs: TypeScript / JavaScript @writehuman/sdk and Python writehuman. Both follow the documented retry policy: a 429, 503 or 504 is retried after the API's Retry-After, at most 2 retries and only when the wait is 60 s or less (both defaults); a longer Retry-After, such as an authentication lockout, is not waited for and the error surfaces at once with it as retry_after / retryAfter. A request that may have been charged is never resent.

TypeScript / JavaScript: wh.humanize(text, { tone, language }), wh.detect(text, { language, includeSentences }), wh.usage(). Every failure throws a subclass of WriteHumanError with code, status and retryAfter; InsufficientBalanceError adds wordsRemaining.
Python: wh.humanize(text, tone=None, language=None), wh.detect(text, language=None, include_sentences=False), wh.usage(). Every failure raises a subclass of WriteHumanError with code, status and retry_after; InsufficientBalanceError adds words_remaining.

// npm install @writehuman/sdk
import { WriteHuman } from "@writehuman/sdk";

const wh = new WriteHuman({ apiKey: "wh_live_your_api_key_here" });
const out = await wh.humanize("Artificial intelligence has revolutionized the way we approach content creation and digital communication.");
console.log(out.results[0]);
console.log(out.words_remaining.total, "words left");

Response

The response format depends on your plan.

{
  "id": "hum_a1b2c3d4e5f6",
  "created": 1778533901580,
  "results": [
    "AI has changed how we create content and communicate online."
  ],
  "scores": null,
  "input_words": 14,
  "words_remaining": {
    "included": 124986,
    "topup": 0,
    "total": 124986
  }
}

Supported Languages

WriteHuman supports 40+ languages. Pass the language name as the language parameter, or omit it for automatic detection.

EnglishChinese (Mandarin)Chinese (Taiwan)FrenchSpanishVietnamesePortugueseJapaneseUkrainianSwedishGermanRussianItalianArabicHindiBengaliKoreanTurkishDutchPolishThaiIndonesianMalayPersianHebrewGreekCzechDanishFinnishNorwegianRomanianHungarianSlovakBulgarianCroatianSerbianSlovenianLithuanianLatvianEstonianUrduSwahiliTagalogAfrikaans

Common Use Cases

Content Marketing

Generate blog posts, product descriptions, and ad copy with AI that reads indistinguishable from human writing.

SEO Agencies

Produce high-volume content that passes AI detection checks before publication.

SaaS Products

AI writing features where the final output needs to be indistinguishable from human writing.

Enterprise Teams

Process internal communications, reports, and documentation generated by large language models.

Support

Contact Support Terms of Service

By using the WriteHuman API you agree to our Terms of Service.