M
API Matrix

Synonyms API

Dictionaries / API Key Intermediate HTTPS
Varies by plan (check documentation)
72 Score
Grade B
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Overview

Synonyms.com API provides synonym, antonym, and thesaurus data for English words, making it useful for writing assistants, word games, and vocabulary tools. Accessing the API requires an API key available via the Synonyms.com website. The response includes related words grouped by relevance and part of speech.

💡

Beginner Tip

Query a single lowercase word at a time for the most reliable results. The response nests synonym groups by part of speech, so iterate over each pos object to collect all related words.

Available Data

word definitions
pronunciation
synonyms and antonyms
example sentences
part of speech

Example Response

JSON Response 
{
  "status": "success",
  "data": {
    "result": "Data from Synonyms",
    "description": "Synonyms, thesaurus and antonyms information for any given word",
    "timestamp": "2025-01-15T10:00:00Z"
  }
}

Field Reference

query The word that was queried.
synonyms Synonym groups organized by part of speech (noun, verb, adjective, etc.).
antonyms Antonym groups organized by part of speech.
related List of related words and phrases not strictly synonymous.

Implementation Example 

const url = "https://www.synonyms.com/";
// Replace headers or query params with the values required by this API.
const response = await fetch(url, {
  headers: {
  "X-API-Key": "YOUR_API_KEY"
  }
});
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

No data returned for a common word The word parameter may be capitalized or contain punctuation.
✓ Always send words in lowercase without punctuation; strip trailing periods or commas before the request.
Authentication error in response body The API key is invalid or has expired.
✓ Retrieve a fresh API key from your Synonyms.com account page and update it in your application.
Unexpected XML response The format parameter was not set to json.
✓ Append &format=json to your request URL to receive JSON instead of the default XML response.

Matrix Score Breakdown

🌐 Reachability 30/30
⚡ Speed 5/20
🔒 Security 15/15
🛠 Developer XP 12/20
✓ Reliability 10/15

Partially tested on Apr 5, 2026

Technical Specifications

Auth API Key
HTTPS REQUIRED
CORS UNKNOWN
Category Dictionaries
Difficulty Intermediate
Verified: 2026-04-04

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