HTML Entities Encoder/Decoder API

About the HTML Entities Encoder/Decoder API

An HTML entities encoder and decoder for making text safe to drop into a page, or for reading encoded markup back as plain characters. Set action to encode for HTML encode (escape) or decode for HTML decode (unescape), POST the string, and get back the converted text with a count of replacements and a list of which characters or entities were involved.

Escaping the characters that carry meaning in HTML is a basic step in XSS prevention when user input ends up in templates, emails or admin screens. The decode direction helps when scraped content, RSS feeds or database exports arrive full of < and " sequences that need to be shown or searched as normal text.

There is no plan difference here: the Free plan and paid plans run the same conversion and return the same fields.

How it works

Encoding replaces six characters with entities: & becomes &, < becomes <, > becomes >, " becomes ", ' becomes ' and / becomes /. Nothing else is touched, so accented letters, emoji and other non-ASCII text pass through unchanged. count is the total number of replacements and entities_replaced lists each distinct character that was replaced, in order of first appearance; the escaped string is returned in encoded.

Decoding first replaces the named forms &, <, >, ", ', / and ', then any decimal ({) or hexadecimal ({) numeric reference. The result is returned in decoded, and entities_decoded lists the named entities found plus the markers &#numeric; and &#xhex; when numeric references were present. Other named entities such as   or © are left as they are.

Two details matter for decode. & is processed before the others, so a double-encoded sequence like < is decoded all the way to < in one call. Numeric references are converted with 16-bit character codes, so references above U+FFFF (most emoji) do not come back as the intended character. Any value other than decode for action is treated as encode.

What people use it for

XSS Prevention

Encode user input before displaying in HTML to prevent cross-site scripting (XSS) attacks

Data Display

Decode HTML entities in stored content to display special characters correctly in web applications

Content Migration

Encode or decode HTML entities when migrating content between systems with different encoding requirements

API Integration

Properly encode HTML content before sending to APIs or decode entities received from external sources

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

Beta

GraphQL

Query language

New

MCP

For AI agents

Request parameters — POST /v1/htmlentities

Sent as JSON in the request body. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Required

Optional

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curl -X POST "https://api.apiverve.com/v1/htmlentities" \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"html":"<div class=\"test\">Hello & World</div>","action":"encode"}'

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.

Response — POST /v1/htmlentities

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.

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{
  "status": "ok",
  "error": null,
  "data": {
    "action": "encode",
    "original": "<div class=\"test\">Hello & World</div>",
    "encoded": "&lt;div class=&quot;test&quot;&gt;Hello &amp; World&lt;&#x2F;div&gt;",
    "entities_replaced": [
      "<",
      "\"",
      ">",
      "&",
      "/"
    ],
    "count": 8
  }
}

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.

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.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

What a call costs — 1 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.

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.

Zero-code embed — one snippet, no backend

Drop an interactive HTML Entities Encoder/Decoder 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 — HTML Entities Encoder/Decoder 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.

Currently v1