JSON to JSONP API

About the JSON to JSONP API

A JSON to JSONP API that wraps JSON data in a callback so it can be loaded with a script tag. POST a JSON object, or a JSON string, with the callback name you want, and get back the finished JSONP text together with the callback name that was used. If you leave the callback out, the name callback is used.

JSONP is still what some older widgets, embedded scripts and legacy browsers expect when a page loads data from another domain without CORS. Rather than hand-assemble the wrapper in each service, you can generate a JSONP response here and serve or cache the result, or use it to produce fixtures for testing code that consumes cross domain JSONP.

The callback name is checked before anything is built, so only a valid JavaScript function name, optionally dotted like MyApp.handlers.load, can come back in the output. The Free plan and paid plans behave the same and return the same two fields.

How it works

The json parameter accepts an object or a string containing JSON; a string is parsed into a value first. The value is then serialised with JSON.stringify, which produces compact output with no added whitespace, and placed inside callback(...);. The full result is returned in jsonp, and the name used is echoed in callback.

callback must match a JavaScript identifier pattern: it starts with a letter, _ or $, continues with letters, digits, _ or $, and may contain dot-separated segments such as app.data.receive. Anything else, including brackets, parentheses, spaces or semicolons, is rejected with a 400 that names the bad value. This check exists because the output is executable script: a callback like alert(1);// would otherwise turn into running code in the caller's page. When callback is omitted, the default name callback is used.

Because the payload passes through JSON.stringify, string contents are escaped the way JSON requires, and key order is kept as received. The response is a JSON document that carries the JSONP text as a string field; it is not served with a JavaScript content type, so write jsonp to your own response or file when you need the script itself.

What people use it for

Cross-Domain Widget Feeds

When third-party embed widgets need cross-domain data without CORS configuration, developers serve JSON payloads wrapped in dynamic client callback functions.

Legacy Portal Maintenance

Engineers supporting legacy enterprise portals convert modern JSON API outputs into JSONP responses so older web clients can parse responses through script tags.

Static Documentation Embeds

Technical writers embed live remote status objects into static HTML documentation sites by wrapping JSON records in custom callback handlers.

Client Mashup Prototyping

To test multi-domain data feeds before updating server headers, frontend developers convert mock JSON datasets into callback-wrapped strings on demand.

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/jsontojsonp

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

1
2
3
4

curl -X POST "https://api.apiverve.com/v1/jsontojsonp" \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"json":{"menu":{"id":"file","value":"File","popup":false}},"callback":"callbackFunction"}'

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/jsontojsonp

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.

1
2
3
4
5
6
7
8

{
  "status": "ok",
  "error": null,
  "data": {
    "callback": "callbackFunction",
    "jsonp": "callbackFunction({\"menu\":{\"id\":\"file\",\"value\":\"File\",\"popup\":false}});"
  }
}

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 JSON to JSONP 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 — JSON to JSONP 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