Developer API
The HumanFlow engine, in your own stack.
One authenticated POST to rewrite AI text so it reads naturally, and one to score it sentence by sentence. Plain JSON, word-based billing, and the same honest rules as the app: we sell volume, not "undetectable".
POST api.humanflow.pro/v1/humanize
{ "text": "In today's fast-paced world…", "tone": "natural" }
// 200 OK
{
"text": "People skim. Write like it.",
"sentences": [ { "score": 0.07 }, … ],
"words_used": 6
}Three endpoints, no SDK required
Plain JSON over HTTPS with a revocable Bearer key. If your language has an HTTP client, you're integrated.
POST/v1/humanize
Humanize text
Send a draft with an optional tone — natural, casual or professional — and get back a rewrite that keeps every claim and changes the rhythm. Billed by input words.
POST/v1/detect
Detect AI text
The same sentence-level read as the app: a per-sentence score plus an overall verdict, so your pipeline can decide what needs another pass — and show its reasoning.
GET/v1/usage
Check usage
Remaining words, plan tier and reset date — read-only, never billed. Query it before a batch job so finance never gets a surprise.
Pay by the word, like everything else here
Same principle as the app plans: every tier gets every feature, and paying more buys volume. Prices are what the plans will cost at launch.
The API is in private beta. There is no public endpoint yet and nothing is charged today — tell us about your use case and we'll set you up with a test key.
Stream
One product, steady flow of words.
$39 /month
≈ $0.26 per 1K humanized words
- Humanize
- 150,000 words / mo
- Detect
- 1,000,000 words / mo
- Per call
- 4,000 words
- Rate limit
- 60 req / min
- API keys
- 3
River
Pipelines, batch jobs, real traffic.
$119 /month
≈ $0.20 per 1K humanized words
- Humanize
- 600,000 words / mo
- Detect
- 4,000,000 words / mo
- Per call
- 12,000 words
- Rate limit
- 150 req / min
- API keys
- 10
Delta
Past River, there is no "unlimited" tier — just a written-down number and a real quote. Tell us your monthly volume and we'll price it plainly, with the same per-word logic as everything above.
Talk to usPrices in USD. Detection is far cheaper for us to run than humanizing, so its allowances are deliberately much larger — same reasoning as the app plans. Need a burst? Top-up packs of 100,000 words are $22 and never expire.
3
tones: natural · casual · professional
0
bypass-rate promises, by design
100%
of features on every tier
API questions
How is usage billed?
By input word count, deducted from your monthly allowance. No token math, no overage surprises — when you're out, calls return a clear error instead of a bill.
Will the output pass detector X?
We make the same non-promise over the API as everywhere else: the rewrite reads naturally, which often lowers scores, but nobody can guarantee another company's detector. That's why /v1/detect returns per-sentence scores — so your product can judge, not hope.
What happens to text sent through the API?
It's processed over encrypted connections solely to produce the response, same as the app. We don't train on your users' text and we don't sell it.
When does the API open?
It is in private beta now. There is no public endpoint and nothing is charged. Tell us what you are building and we will set you up with a test key and a date.
Build with the honest humanizer.
Tell us what you're building and we'll get you a beta key.
Request accessOr email support@humanflow.pro
Want it inside your assistant instead of your codebase? The MCP connector →