Fill in the Blanks Generator API Reference

Overview

Returns puzzles with answers, letter counts, and optional hints. Includes printable HTML for offline use.

Endpoint

One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.

GEThttps://api.apiverve.com/v1/fillintheblanks

curl "https://api.apiverve.com/v1/fillintheblanks?category=idioms&count=5&difficulty=medium&image=true" \
  -H "x-api-key: your_api_key_here"

const res = await fetch('https://api.apiverve.com/v1/fillintheblanks?category=idioms&count=5&difficulty=medium&image=true', {
  headers: { 'x-api-key': 'your_api_key_here' },
});

if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);

const { data } = await res.json();
console.log(data);

import requests

res = requests.get(
    "https://api.apiverve.com/v1/fillintheblanks?category=idioms&count=5&difficulty=medium&image=true",
    headers={"x-api-key": "your_api_key_here"},
    timeout=15,
)
res.raise_for_status()

print(res.json()["data"])

package main

import (
	"fmt"
	"io"
	"net/http"
)

func main() {
	req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/fillintheblanks?category=idioms&count=5&difficulty=medium&image=true", nil)
	req.Header.Set("x-api-key", "your_api_key_here")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()

	out, _ := io.ReadAll(res.Body)
	fmt.Println(string(out))
}

Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.

Authentication

Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.

401 is the only auth verdict

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.

Parameters

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them.

Parameter	Type	Description
`category`Optional	string	Puzzle category `randomidiomsproverbsquotessciencegeography` default random
`count`Optional	integer	Number of puzzles default 5 · range 1–20
`difficulty`Optional	string	Difficulty level `easymediumhard` default medium
`image`OptionalPremium	boolean	Set to true to generate a downloadable puzzle image

Response

Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.

Sample response

{
  "status": "ok",
  "error": null,
  "data": {
    "puzzles": [
      {
        "id": 1,
        "sentence": "A penny saved is a penny ___.",
        "answer": "EARNED",
        "letterCount": 6,
        "hint": "gained/obtained",
        "firstLetter": null
      },
      {
        "id": 2,
        "sentence": "Actions speak louder than ___.",
        "answer": "WORDS",
        "letterCount": 5,
        "hint": "what we say",
        "firstLetter": null
      },
      {
        "id": 3,
        "sentence": "Don't count your chickens before they ___.",
        "answer": "HATCH",
        "letterCount": 5,
        "hint": "come out of eggs",
        "firstLetter": null
      },
      {
        "id": 4,
        "sentence": "The early bird catches the ___.",
        "answer": "WORM",
        "letterCount": 4,
        "hint": "a crawling creature",
        "firstLetter": null
      },
      {
        "id": 5,
        "sentence": "Don't put all your eggs in one ___.",
        "answer": "BASKET",
        "letterCount": 6,
        "hint": "a container",
        "firstLetter": null
      }
    ],
    "count": 5,
    "difficulty": "medium",
    "category": "idioms",
    "html": "<html><head><title>Fill in the Blanks</title><style>body {font-family: Arial, sans-serif; padding: 20px; max-width: 700px; margin: 0 auto;}h1 {text-align: center; color: #673AB7;}.puzzle {background: #f5f5f5; padding: 20px; margin: 15px 0; border-radius: 10px;}.number {font-weight: bold; color: #673AB7; margin-bottom: 10px;}.sentence {font-size: 18px; line-height: 1.8;}.blank {display: inline-block; min-width: 100px; border-bottom: 2px solid #673AB7; margin: 0 5px;}.hint {font-size: 13px; color: #888; font-style: italic; margin-top: 10px;}.info {font-size: 12px; color: #999; margin-top: 5px;}</style></head><body><h1>Fill in the Blanks</h1><div class='puzzle'><div class='number'>#1</div><div class='sentence'>A penny saved is a penny <span class='blank'></span>.</div><div class='info'>6 letters</div><div class='hint'>Hint: gained/obtained</div></div><div class='puzzle'><div class='number'>#2</div><div class='sentence'>Actions speak louder than <span class='blank'></span>.</div><div class='info'>5 letters</div><div class='hint'>Hint: what we say</div></div><div class='puzzle'><div class='number'>#3</div><div class='sentence'>Don't count your chickens before they <span class='blank'></span>.</div><div class='info'>5 letters</div><div class='hint'>Hint: come out of eggs</div></div><div class='puzzle'><div class='number'>#4</div><div class='sentence'>The early bird catches the <span class='blank'></span>.</div><div class='info'>4 letters</div><div class='hint'>Hint: a crawling creature</div></div><div class='puzzle'><div class='number'>#5</div><div class='sentence'>Don't put all your eggs in one <span class='blank'></span>.</div><div class='info'>6 letters</div><div class='hint'>Hint: a container</div></div></body></html>",
    "image": {
      "imageName": "ba85c6d6-4376-4171-841d-8b4bc97e1095_fillblanks.png",
      "format": ".png",
      "downloadURL": "https://storage.googleapis.com/apiverve/APIData/fillintheblanks/ba85c6d6-4376-4171-841d-8b4bc97e1095_fillblanks.png?GoogleAccessId=635500398038-compute%40developer.gserviceaccount.com&Expires=1766010206&Signature=YRHfh28GKDNvEM4Q07qRcNyg3WnPs7Ee7yg0xXKxKRTmT%2Bg3x%2FThpfWsFTeYScpZlgQTVQ3SU1tZMGH74sZJvAHdVkG6IGA9V2lwIfhHzcfu4Uf4VGKL8%2FIa%2FaLupdtrgDqXSFWOJ9EHHeMKnImAhli1qhlMu%2BIuWAiqfPitDlN5pMklv4R5FACKkZld4LXyA82%2BX8bt%2FESyHciZ5jzlqY1JTacL4kW5uK09bpoo9Ytvs8XOOOjB0my1s%2BIq5z0JEwZzw1Jag%2F5vd09wTXzSXeQMzfo%2FDj73kpU7SilAxEGh%2BuflilyDQTXK7krXcdFUGcD5Nd4Wm%2BW7dP8tQKmbAA%3D%3D",
      "expires": 1766010206793
    }
  }
}

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
`puzzles`	array[5]		Array of fill-in-the-blanks puzzle objects
`id`	number	`1`	Unique identifier for the puzzle
`sentence`	string	`"A penny saved is a penny ___."`	Full sentence with blank to be filled in
`answer`	string	`"EARNED"`	Correct answer word to fill the blank
`letterCount`	number	`6`	Number of letters in the answer
`hint`	string	`"gained/obtained"`	Helpful hint describing the answer
`firstLetter`	object	`null`	First letter of answer or null if not provided
`count`	number	`5`	Total number of puzzles generated
`difficulty`	string	`"medium"`	Difficulty level of the puzzles
`category`	string	`"idioms"`	Category of the puzzles
`html`Premium	string	"<html><head><title>Fill in the Blanks</title><style>body {font-family: Arial, sans-serif; padding: 20px; max-width: 700px; margin: 0 auto;}h1 {text-align: center; color: #673AB7;}.puzzle {background: #f5f5f5; padding: 20px; margin: 15px 0; border-radius: 10px;}.number {font-weight: bold; color: #673AB7; margin-bottom: 10px;}.sentence {font-size: 18px; line-height: 1.8;}.blank {display: inline-block; min-width: 100px; border-bottom: 2px solid #673AB7; margin: 0 5px;}.hint {font-size: 13px; color: #888; font-style: italic; margin-top: 10px;}.info {font-size: 12px; color: #999; margin-top: 5px;}</style></head><body><h1>Fill in the Blanks</h1><div class='puzzle'><div class='number'>#1</div><div class='sentence'>A penny saved is a penny <span class='blank'></span>.</div><div class='info'>6 letters</div><div class='hint'>Hint: gained/obtained</div></div><div class='puzzle'><div class='number'>#2</div><div class='sentence'>Actions speak louder than <span class='blank'></span>.</div><div class='info'>5 letters</div><div class='hint'>Hint: what we say</div></div><div class='puzzle'><div class='number'>#3</div><div class='sentence'>Don't count your chickens before they <span class='blank'></span>.</div><div class='info'>5 letters</div><div class='hint'>Hint: come out of eggs</div></div><div class='puzzle'><div class='number'>#4</div><div class='sentence'>The early bird catches the <span class='blank'></span>.</div><div class='info'>4 letters</div><div class='hint'>Hint: a crawling creature</div></div><div class='puzzle'><div class='number'>#5</div><div class='sentence'>Don't put all your eggs in one <span class='blank'></span>.</div><div class='info'>6 letters</div><div class='hint'>Hint: a container</div></div></body></html>"	Printable HTML rendering of all puzzles
`image`Premium	object	`{...}`	Generated puzzle image details and download information
`imageName`Premium	string	`"ba85c6d6-4376-4171-841d-8b4bc97e1095_fillblanks.png"`	Unique filename of generated puzzle image
`format`Premium	string	`".png"`	Image file format (.png, .jpg, etc)
`downloadURL`Premium	string	"https://storage.googleapis.com/apiverve/APIData/fillintheblanks/ba85c6d6-4376-4171-841d-8b4bc97e1095_fillblanks.png?GoogleAccessId=635500398038-compute%40developer.gserviceaccount.com&Expires=1766010206&Signature=YRHfh28GKDNvEM4Q07qRcNyg3WnPs7Ee7yg0xXKxKRTmT%2Bg3x%2FThpfWsFTeYScpZlgQTVQ3SU1tZMGH74sZJvAHdVkG6IGA9V2lwIfhHzcfu4Uf4VGKL8%2FIa%2FaLupdtrgDqXSFWOJ9EHHeMKnImAhli1qhlMu%2BIuWAiqfPitDlN5pMklv4R5FACKkZld4LXyA82%2BX8bt%2FESyHciZ5jzlqY1JTacL4kW5uK09bpoo9Ytvs8XOOOjB0my1s%2BIq5z0JEwZzw1Jag%2F5vd09wTXzSXeQMzfo%2FDj73kpU7SilAxEGh%2BuflilyDQTXK7krXcdFUGcD5Nd4Wm%2BW7dP8tQKmbAA%3D%3D"	Temporary download URL for puzzle image
`expires`Premium	number	`1766010206793`	Timestamp when download URL expires

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.

Status	Meaning	What to do
`400`	Input was rejected	Read `error`; it names the parameter.
`401`	Key missing or invalid	Check the header name and the key value.
`403`	Key valid, but not permitted	A key restriction or IP allow-list; see key scoping.
`429`	Rate limited, or out of credits	Read `error` to tell them apart; see rate limits.

Use cases

Education: Create vocabulary and comprehension tests
Language Learning: Build idiom and proverb exercises
Trivia Games: Generate knowledge-testing puzzles
Worksheets: Produce printable educational materials

Other ways to use Fill in the Blanks Generator

Set up Fill in the Blanks Generator on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.

Give it to an AI agentConnect over MCP and your agent calls it as a native tool — Claude, Cursor, ChatGPT.VerveKit →Reference →

Fill in the Blanks Generator