--- title: "Fake Signup Detection & Email Validation API | SignupSieve" description: "Catch fake signups, not just bad emails. One API call returns a human score, a verdict and the reasons. Free plan, no card needed." canonical_url: "https://signupsieve.pages.dev/" meta: "og:description": "Catch fake signups, not just bad emails. One API call returns a human score, a verdict and the reasons. Free plan, no card needed." "og:image": "https://signupsieve.pages.dev/_og/s/o_4d52d6e8c5e10479.png" "og:image:height": "600" "og:image:type": image/png "og:image:width": "1200" "og:title": "Fake Signup Detection & Email Validation API | SignupSieve" "twitter:image": "https://signupsieve.pages.dev/_og/s/o_4d52d6e8c5e10479.png" --- > Index of every page on this site: [llms.txt](https://signupsieve.pages.dev/llms.txt) # Catch fake signups,not just bad emails. One API call tells you if a real, unique person is behind an email address. A score, a verdict and the reasons, in milliseconds. [Get free API key](https://rapidapi.com/KeirStephanCTombocon/api/signupsieve) [Try the free checker](https://signupsieve.pages.dev/free-email-checker) Free plan: 1,000 checks a month. No card needed. Incoming - maria.santos@gmail.comchecking - qwerty99@mailinator.com - john+7@gmail.com - a.lee@acme.com - xk7qv2@temp-mail.org - john@gmial.com - priya.n@outlook.com \~3 ms of processing per check. No email is ever sent. Checking maria.santos@gmail.com 1. **โœ“**Domain**gmail.com accepts mail** 2. **โœ“**Name & aliases**Natural name** 3. **โœ“**Crowd & IP**First time seen** **94****allow** Sorted Allow2 - priya.n@outlook.com - a.lee@acme.com Review1 - john+7@gmail.com Block4 - dfghj6638@yahoo.com - john@gmial.com - xk7qv2@temp-mail.org What it catches ## Bad emails are the easy part. Fake people are the expensive part. Everything a basic email validator misses, in one call. ### One person, many accounts Gmail dots and +tags all reach the same inbox. We return the real one, so a unique index stops repeat free trials. - john+1@gmail.com - j.ohn+2@gmail.com - jo.hn+trial@gmail.com john@gmail.com canonical ### Throwaway emails, even new ones - mailinator.comdisposable - temp-mail.orgdisposable - brand-new-x7.xyzshared servers 12,000+ known domains, plus new ones caught by their mail servers. ### Fake name detection qwerty1234@yahoo.comblock maria.santos@gmail.comallow Spots keyboard mash and random strings. A real name is never blocked on its own. ### Typo fix john@gm~~ia~~l.com john@gm**ai**l.com did\_you\_mean Suggest the fix instead of rejecting a real customer. ### IP checks - cloud server - Tor exit node - many signups, one IP Optional: send the user's IP and catch bots behind it. ### Learns from you Report what happened to a signup, for free. After about 50 outcomes, your own model starts serving, but only once it beats the rules on your traffic. ``` curl -X POST "https://signupsieve.p.rapidapi.com/v1/check" \ -H "Content-Type: application/json" \ -H "X-RapidAPI-Key: YOUR_RAPIDAPI_KEY" \ -H "X-RapidAPI-Host: signupsieve.p.rapidapi.com" \ -d '{"email": "maria.santos@gmail.com", "ip": "203.177.10.10"}' ``` **Response **200 OK ``` { "email": "maria.santos@gmail.com", "canonical": "mariasantos@gmail.com", "account_type": "free", "role_account": false, "disposable": false, "relay": false, "deliverable_domain": true, "mail_provider": "google", "human_score": 94, "verdict": "allow", "reasons": ["natural_name", "dotted_gmail"], "ip": { "tor": false, "signups_from_ip": 1 }, "check_id": "chk_AXDmekmC35NL1mpGtCtC...", "model": "baseline" } ``` Benchmark ## Honest numbers Measured on public domain lists and names, with the hand-tuned model and no customer feedback. No real person's email was used. 0**%** **real people wrongly blocked** 1,709 of 1,709 real addresses kept 100**%** **domain typos fixed** 217 of 217 typos corrected **\~**70**%** **bot addresses caught** 70.2% of 1,200 generated bots Pricing ## Start free. Pay as you grow. Every plan includes every feature. Feedback calls are free, and failed requests are never billed. [**Compare plans**](https://signupsieve.pages.dev/pricing) **Signups you check a month ****25,000** 5001M **Best fit** **Pro****$19**/mo Fits inside the plan, no extra charges. 1. ### **Basic** **$0****/month** - **1,000** emails a month - Stops at the limit, no card needed - Every feature included [Start free](https://rapidapi.com/KeirStephanCTombocon/api/signupsieve) 2. ### **Pro****Best fit** **$19****/month** - **25,000** emails a month - Then $0.001 per extra email - Every feature included [Choose Pro](https://rapidapi.com/KeirStephanCTombocon/api/signupsieve/pricing) 3. ### **Ultra** **$49****/month** - **100,000** emails a month - Then $0.0008 per extra email - Every feature included [Choose Ultra](https://rapidapi.com/KeirStephanCTombocon/api/signupsieve/pricing) 4. ### **Mega** **$149****/month** - **500,000** emails a month - Then $0.0005 per extra email - Every feature included [Choose Mega](https://rapidapi.com/KeirStephanCTombocon/api/signupsieve/pricing) **SignupSieve** Usually replies in a few ms Hi! I'm SignupSieve. Tap Questions to browse, or type below. Does it send an email or ping the mailbox? No. Many validators do SMTP "pings", which are slow and can get your IP blacklisted. SignupSieve uses DNS, domain data, name analysis and crowd signals instead.
**Does it send an email or ping the mailbox?**
No. Many validators do SMTP "pings", which are slow and can get your IP blacklisted. SignupSieve uses DNS, domain data, name analysis and crowd signals instead.
**Will it block real people with unusual names?**
A name alone can never cause block, only review. On public test data, 0% of real company emails and real names were wrongly blocked.
**Are Apple Hide My Email users flagged?**
No. Privacy relays such as Apple Hide My Email and Firefox Relay are marked relay: true and scored as real people.
**How fast is it?**
Usually a few milliseconds of processing per check, plus network time. A bulk check of 1,000 addresses takes well under a second of processing.
**Can it tell me whether a mailbox exists?**
No. It tells you whether the domain accepts mail and whether a real, unique person is likely behind the address. For stopping fake signups, that is what matters.
**What should I do with a "review" verdict?**
Let them in, but ask for something first: email verification, a CAPTCHA or a phone check before you hand out free credits.
**Does it get better over time?**
Yes. Report outcomes to /v1/feedback for free and the model learns in real time. GET /v1/model shows its live accuracy.
**Can it prevent multiple accounts from one person?**
Yes. Every check returns canonical, the real inbox behind Gmail dots and +tags. Put a unique index on it and one person can't open ten accounts. We also flag an inbox when we see many spellings of it.
**What is the Gmail dot trick?**
Gmail ignores dots and anything after a +, so john.doe@gmail.com, johndoe+1@gmail.com and j.o.h.n.doe@gmail.com all reach one inbox. People use it to grab repeat free trials. SignupSieve returns the one real address so you can spot it.
**Does it stop free trial abuse and bot signups?**
That is what it is built for. It catches throwaway emails, repeat accounts, bot-like names, cloud-server and Tor IPs, and bursts of signups at one domain, so you can stop fake signups before they use your free credits.
**Is it a disposable email API or an email verification API?**
Both, and more: it is a signup fraud API. It detects disposable domains and checks the domain can receive mail, then adds name, alias, IP and crowd signals to tell you if a real, unique person signed up.
Pass it on ## Know a team drowning in fake signups? Send them SignupSieve. The free plan covers 1,000 checks a month, no card needed. We checked: whoever shares it is a real human with good taste. refer.sh $ signupsieve refer --to "a team drowning in fake signups" 200 OK ยท 3 ms { "human\_score": 100, "verdict": "allow", "reasons": \["real\_human", "good\_taste"], "share\_url": "https://signupsieve.pages.dev/" } ready - [**POST** /share/x](https://x.com/intent/post?text=SignupSieve%20catches%20fake%20signups%2C%20not%20just%20bad%20emails.%20Free%20plan%3A%201%2C000%20checks%20a%20month.&url=https%3A%2F%2Fsignupsieve.pages.dev%2F) - [**POST** /share/linkedin](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fsignupsieve.pages.dev%2F) - [**POST** /share/reddit](https://www.reddit.com/submit?url=https%3A%2F%2Fsignupsieve.pages.dev%2F&title=SignupSieve%20catches%20fake%20signups%2C%20not%20just%20bad%20emails.%20Free%20plan%3A%201%2C000%20checks%20a%20month.) - [**POST** /share/whatsapp](https://wa.me/?text=SignupSieve%20catches%20fake%20signups%2C%20not%20just%20bad%20emails.%20Free%20plan%3A%201%2C000%20checks%20a%20month.%20https%3A%2F%2Fsignupsieve.pages.dev%2F) - [**POST** /share/email](mailto:?subject=Stop%20fake%20signups%20with%20SignupSieve&body=SignupSieve%20catches%20fake%20signups%2C%20not%20just%20bad%20emails.%20Free%20plan%3A%201%2C000%20checks%20a%20month.%0A%0Ahttps%3A%2F%2Fsignupsieve.pages.dev%2F) ```json {"@context":"https://schema.org","@graph":[{"@id":"https://signupsieve.pages.dev/#website","@type":"WebSite","description":"Catch fake signups, not just bad emails. 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SignupSieve uses DNS, domain data, name analysis and crowd signals instead."}},{"@id":"https://signupsieve.pages.dev/#/schema/question/2","@type":"Question","inLanguage":"en","name":"Will it block real people with unusual names?","acceptedAnswer":{"@type":"Answer","text":"A name alone can never cause block, only review. On public test data, 0% of real company emails and real names were wrongly blocked."}},{"@id":"https://signupsieve.pages.dev/#/schema/question/3","@type":"Question","inLanguage":"en","name":"Are Apple Hide My Email users flagged?","acceptedAnswer":{"@type":"Answer","text":"No. Privacy relays such as Apple Hide My Email and Firefox Relay are marked relay: true and scored as real people."}},{"@id":"https://signupsieve.pages.dev/#/schema/question/4","@type":"Question","inLanguage":"en","name":"How fast is it?","acceptedAnswer":{"@type":"Answer","text":"Usually a few milliseconds of processing per check, plus network time. A bulk check of 1,000 addresses takes well under a second of processing."}},{"@id":"https://signupsieve.pages.dev/#/schema/question/5","@type":"Question","inLanguage":"en","name":"Can it tell me whether a mailbox exists?","acceptedAnswer":{"@type":"Answer","text":"No. It tells you whether the domain accepts mail and whether a real, unique person is likely behind the address. For stopping fake signups, that is what matters."}},{"@id":"https://signupsieve.pages.dev/#/schema/question/6","@type":"Question","inLanguage":"en","name":"What should I do with a \"review\" verdict?","acceptedAnswer":{"@type":"Answer","text":"Let them in, but ask for something first: email verification, a CAPTCHA or a phone check before you hand out free credits."}},{"@id":"https://signupsieve.pages.dev/#/schema/question/7","@type":"Question","inLanguage":"en","name":"Does it get better over time?","acceptedAnswer":{"@type":"Answer","text":"Yes. Report outcomes to /v1/feedback for free and the model learns in real time. GET /v1/model shows its live accuracy."}},{"@id":"https://signupsieve.pages.dev/#/schema/question/8","@type":"Question","inLanguage":"en","name":"Can it prevent multiple accounts from one person?","acceptedAnswer":{"@type":"Answer","text":"Yes. Every check returns canonical, the real inbox behind Gmail dots and +tags. Put a unique index on it and one person can't open ten accounts. We also flag an inbox when we see many spellings of it."}},{"@id":"https://signupsieve.pages.dev/#/schema/question/9","@type":"Question","inLanguage":"en","name":"What is the Gmail dot trick?","acceptedAnswer":{"@type":"Answer","text":"Gmail ignores dots and anything after a +, so john.doe@gmail.com, johndoe+1@gmail.com and j.o.h.n.doe@gmail.com all reach one inbox. People use it to grab repeat free trials. SignupSieve returns the one real address so you can spot it."}},{"@id":"https://signupsieve.pages.dev/#/schema/question/10","@type":"Question","inLanguage":"en","name":"Does it stop free trial abuse and bot signups?","acceptedAnswer":{"@type":"Answer","text":"That is what it is built for. It catches throwaway emails, repeat accounts, bot-like names, cloud-server and Tor IPs, and bursts of signups at one domain, so you can stop fake signups before they use your free credits."}},{"@id":"https://signupsieve.pages.dev/#/schema/question/11","@type":"Question","inLanguage":"en","name":"Is it a disposable email API or an email verification API?","acceptedAnswer":{"@type":"Answer","text":"Both, and more: it is a signup fraud API. It detects disposable domains and checks the domain can receive mail, then adds name, alias, IP and crowd signals to tell you if a real, unique person signed up."}},{"@id":"https://signupsieve.pages.dev/#logo","@type":"ImageObject","caption":"SignupSieve","contentUrl":"https://signupsieve.pages.dev/signupsieve-app-icon-1024.png","inLanguage":"en","url":"https://signupsieve.pages.dev/signupsieve-app-icon-1024.png"}]} ``` ## Sitemap See the full [sitemap](https://signupsieve.pages.dev/sitemap.md) for all pages.