Verify human visitors with ready-to-solve image captchas.
Captcha Generator generates visual captcha challenges with signed image URLs and text solutions. Each request delivers a challenge image, its correct answer string, an expiration timestamp, and a unique identifier.
Try it — live request, no key required
No key required to try it. Get a key to use it in your app.
{
"status": "ok",
"error": null,
"data": {
"id": "e183c54c-5bf6-455e-bc96-195685cee71c",
"expires": 1766010041360,
"solution": "fwvct",
"downloadURL": "https://storage.googleapis.com/apiverve/APIData/captchagenerator/e183c54c-5bf6-455e-bc96-195685cee71c.png?GoogleAccessId=635500398038-compute%40developer.gserviceaccount.com&Expires=1766010041&Signature=LLBhTrpVAk%2Bzx%2B2U7sdbIfjUOm%2FEe4hP7ebqGfphThctFRbHs9oyHPJ3J7BCAu71WswQr1qOKh%2BQddOPTGFCVUVL%2BlN1Qxt%2BlIBXYVM7%2FzW3YlfbHmFbXaesr%2BC7pFW6ekZ88fobbOP%2FcGbKdtVL1Vz9ceomtqUw%2Bl9Mwy3FCkpmwPHzGxW56%2BAHB%2B5TQgH2S%2FcmkJkPUxMSGnztQerMNB7V2JrhpuBLZl7N%2FPRucwJswVX6LYYOfNlvrFuxwJwS%2BBot9TesdYlPPDZgOfBo0%2FGgGMzIc753aPUIzkJoeMyPZgJGRilPQNrWJgp%2F7mmx4WNq6QgdIZPlQ36FlDHMsg%3D%3D"
}
}
About the Captcha Generator API
Sending a request creates a fresh captcha challenge without requiring query parameters. The response provides a signed download URL to serve the challenge graphic to users, the correct solution string to verify their submission on your server, a unique challenge ID, and a millisecond expiration timestamp.
What people use it for
- Registration Form Protection
- To block automated spam registrations, web apps fetch a challenge image for the signup form and check submitted text against the returned solution.
- Failed Login Throttling
- When visitors trigger multiple failed login attempts, authentication services display a captcha image to verify that a person is behind the keyboard.
- Contact Form Verification
- Community forums attach challenge images to public inquiry forms, using the millisecond expiration timestamp to invalidate stale submissions.
- Password Reset Defense
- Require visitors to solve a visual challenge before sending password reset links to prevent bad actors from triggering bulk recovery emails.
Ways to call it
One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.
- JSON
- Default REST response
- XML
- Markup format
- YAML
- Human-readable
- CSV
- Tabular export
- GraphQL
- Query language
- MCP
- For AI agents
Other ways to use Captcha Generator
Same data, same APIVerve account, same credit balance — one key works on all of them.
Is it cheap enough to generate a captcha for every form submission?
How do I display the generated captcha to a visitor?
How does answer verification work?
What happens when a captcha expires?
Can I customize the character set or difficulty?
Request parameters — GET /v1/captchagenerator
Call it with your key and nothing else. Any query string you send is ignored rather than rejected.
curl "https://api.apiverve.com/v1/captchagenerator" \
-H "x-api-key: YOUR_API_KEY"Authentication
Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.
| Header | When | Value |
|---|---|---|
x-api-keyRequired | Every request | Your API key. Header names are case-insensitive, so X-API-Key is the same header. |
AuthorizationAlternate | Instead of the above | Bearer <key> — for clients that only expose bearer auth. Resolves to the same account and the same billing. |
A 401 means the key is missing, invalid or expired. A 403 means the key is valid but not permitted here — blocked by a key restriction or an IP allow-list. Running out of credits is a 429.
Response — GET /v1/captchagenerator
Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.
{
"status": "ok",
"error": null,
"data": {
"id": "e183c54c-5bf6-455e-bc96-195685cee71c",
"expires": 1766010041360,
"solution": "fwvct",
"downloadURL": "https://storage.googleapis.com/apiverve/APIData/captchagenerator/e183c54c-5bf6-455e-bc96-195685cee71c.png?GoogleAccessId=635500398038-compute%40developer.gserviceaccount.com&Expires=1766010041&Signature=LLBhTrpVAk%2Bzx%2B2U7sdbIfjUOm%2FEe4hP7ebqGfphThctFRbHs9oyHPJ3J7BCAu71WswQr1qOKh%2BQddOPTGFCVUVL%2BlN1Qxt%2BlIBXYVM7%2FzW3YlfbHmFbXaesr%2BC7pFW6ekZ88fobbOP%2FcGbKdtVL1Vz9ceomtqUw%2Bl9Mwy3FCkpmwPHzGxW56%2BAHB%2B5TQgH2S%2FcmkJkPUxMSGnztQerMNB7V2JrhpuBLZl7N%2FPRucwJswVX6LYYOfNlvrFuxwJwS%2BBot9TesdYlPPDZgOfBo0%2FGgGMzIc753aPUIzkJoeMyPZgJGRilPQNrWJgp%2F7mmx4WNq6QgdIZPlQ36FlDHMsg%3D%3D"
}
}
Response fields
Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.
| Field | Type | Example | Description |
|---|---|---|---|
id | string | "e183c54c-5bf6-455e-bc96-195685cee71c" | Unique identifier for the generated captcha |
expires | number | 1766010041360 | Unix timestamp when captcha expires in milliseconds |
solution | string | "fwvct" | The correct answer string for the captcha |
downloadURL | string | "https://storage.googleapis.com/apiverve/APIData/captchagenerator/e183c54c-5bf6-455e-bc96-195685cee71c.png?GoogleAccessId=635500398038-compu… | Download URL for the captcha image with signature |
Response headers
Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.
| Header | What it carries |
|---|---|
x-api-remaining-credits | Credits left in the current cycle |
x-api-credits-used | Credits spent in the current cycle |
x-api-max-credits | The allowance for the cycle |
x-api-version | Version of the endpoint that answered |
Errors
Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.
| Status | Meaning | What to do |
|---|---|---|
400 | Input was rejected | Read error; it names the parameter that has to change. |
401 | Key missing or invalid | Check the header name and the key value. |
403 | Key valid, but not permitted here | A key restriction or an IP allow-list — never a bad key. |
429 | Rate limited, or out of credits | Read error to tell them apart, then back off or top up. |
What a call costs — 10 credits per call
Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.
| Plan | Per month | Credits | Captcha Generator calls | Per 1,000 calls |
|---|---|---|---|---|
| Free | Free | 200 | 20 | Free |
| Starter | $29.99 | 200,000 | 20,000 | $1.50 |
| Pro | $99.99 | 1,000,000 | 100,000 | $1.00 |
| Mega | $299.99 | 4,000,000 | 400,000 | $0.75 |
Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.
Call it from cURL — GET /v1/captchagenerator
No SDK to install — this is a plain HTTPS call to /v1/captchagenerator with your key in the x-api-key header. Swap in a real key and it runs as-is.
curl "https://api.apiverve.com/v1/captchagenerator" \
-H "x-api-key: YOUR_API_KEY"Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Node.js — GET /v1/captchagenerator
Install the Node.js SDK, then call the Captcha Generator API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.
npm install @apiverve/captchageneratorconst res = await fetch("https://api.apiverve.com/v1/captchagenerator", {
headers: { "x-api-key": "YOUR_API_KEY" },
});
const { data } = await res.json();
console.log(data);Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Python — GET /v1/captchagenerator
Install the Python SDK, then call the Captcha Generator API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.
pip install apiverve-captchageneratorimport requests
res = requests.get(
"https://api.apiverve.com/v1/captchagenerator",
headers={"x-api-key": "YOUR_API_KEY"},
)
print(res.json()["data"])Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from C# / .NET — GET /v1/captchagenerator
Install the C# / .NET SDK, then call the Captcha Generator API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.
dotnet add package APIVerve.API.CaptchaGeneratorusing var client = new HttpClient();
client.DefaultRequestHeaders.Add("x-api-key", "YOUR_API_KEY");
var json = await client.GetStringAsync("https://api.apiverve.com/v1/captchagenerator");
Console.WriteLine(json);Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Go — GET /v1/captchagenerator
No SDK to install — this is a plain HTTPS call to /v1/captchagenerator with your key in the x-api-key header. Swap in a real key and it runs as-is.
req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/captchagenerator", nil)
req.Header.Set("x-api-key", "YOUR_API_KEY")
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from PHP — GET /v1/captchagenerator
No SDK to install — this is a plain HTTPS call to /v1/captchagenerator with your key in the x-api-key header. Swap in a real key and it runs as-is.
$ch = curl_init("https://api.apiverve.com/v1/captchagenerator");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-api-key: YOUR_API_KEY"]);
$response = curl_exec($ch);
echo $response;Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Ruby — GET /v1/captchagenerator
No SDK to install — this is a plain HTTPS call to /v1/captchagenerator with your key in the x-api-key header. Swap in a real key and it runs as-is.
require "net/http"
uri = URI("https://api.apiverve.com/v1/captchagenerator")
req = Net::HTTP::Get.new(uri)
req["x-api-key"] = "YOUR_API_KEY"
res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |h| h.request(req) }
puts res.bodyResources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Zero-code embed — one snippet, no backend
Drop an interactive Captcha Generator form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.
Changelog — Captcha Generator API
Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.
Entries are picked up from dated catalog snapshots, so the first one appears after the next snapshot that moves something. A period where nothing changed produces no entry — silence is a valid changelog for the Captcha Generator API.
Data Generation
- Acronym Generator
- Baby Name Generator
- Barcode Generator
- Bingo Card Generator
- Boggle Board Generator
- Captcha Generator
- Chart Generator
- Color Palette Generator
- Comment Generator
- Company Name Generator
- Cron Expression Generator
- Cuid Generator
- GUID Generator
- Hashtag Generator
- IMEI Generator
- Initialism Generator
- JSON Schema Generator
- Lorem Ipsum Generator
- Password Generator
- QR Code Generator
- Random Data Generator
- Random Identity Generator
- Random User Generator
- Random Word
- Short Code Generator
- Sitemap Generator
- Test Card Generator
- TOTP Generator
- ULID Generator
- User Agent Generator
- Username Generator
- UUID Generator