Number Base Converter API

About the Number Base Converter API

A number base converter API for base conversion between any radix from 2 to 36. Send a number and its source base, and either name a target base or leave it out to get the common ones at once. Common conversions include binary to decimal, decimal to binary, hex to decimal and octal to decimal, and the response also labels each base by name so a UI can show "hexadecimal" rather than 16.

Developers use it in calculators and teaching tools, when reading register values and bit masks, when decoding IDs written in base 36, and in data pipelines that receive numbers in mixed formats. Invalid digits for the chosen base are rejected rather than quietly truncated, and very long values are converted digit by digit so they do not lose precision.

Every plan, including the Free plan, gets the same conversion and the same fields.

How it works

The input value is checked against the digits allowed for from before any conversion: base 8 accepts 0 to 7, base 16 accepts 0 to 9 and A to F, and so on up to base 36 with all letters. Letters are case-insensitive and a leading minus sign is allowed. A digit outside the base returns a 400, unlike JavaScript's parseInt, which stops at the first bad character. Both bases must be between 2 and 36; from defaults to 10.

Conversion is done by long division over the digit array instead of through a floating-point number, so results stay exact at any length. decimal_value_exact is the base-10 value as a string and is always exact. decimal_value is the same value as a JSON number for convenience; past 2^53 (9,007,199,254,740,992) it is rounded, so read decimal_value_exact for large inputs.

When to is set, output_value holds the converted digits in upper case, with output_base and output_base_name. Names are binary, octal, decimal and hexadecimal for 2, 8, 10 and 16, and base-N for every other base. When to is omitted, the response has no output_value; instead a conversions object gives binary, octal, decimal, hexadecimal, base32 and base36 together. Note that base32 here is plain radix-32 digits (0-9, A-V), not RFC 4648 Base32 encoding.

What people use it for

Programming

Convert between binary, octal, decimal, and hexadecimal for programming and debugging

Computer Science Education

Teach number systems and base conversion concepts in educational tools

Data Encoding

Convert between different number representations for data encoding and decoding

Network Analysis

Work with hexadecimal values in network protocols and packet analysis

Without writing code

The Base Converter widget from WidgetSpark converts binary, hex and decimal from your desktop.

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 — GET /v1/numberbaseconverter

Sent in the query string. 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 "https://api.apiverve.com/v1/numberbaseconverter?value=FF&from=16&to=10" \
  -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.

Response — GET /v1/numberbaseconverter

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": {
    "input_value": "FF",
    "input_base": 16,
    "input_base_name": "hexadecimal",
    "decimal_value": 255,
    "decimal_value_exact": "255",
    "output_value": "255",
    "output_base": 10,
    "output_base_name": "decimal"
  }
}

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 Number Base Converter 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 — Number Base Converter 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