# NetworkCalc

> NetworkCalc is a free web app and REST API for network operations, IP math, DNS diagnostics, website security checks, and encoding utilities.

NetworkCalc is built for network administrators, sysadmins, IT teams, developers, students, and support engineers who need quick answers without signup friction. The site offers browser-based tools and matching JSON API endpoints so workflows can be used interactively or automated in scripts, dashboards, and internal tooling.

## What NetworkCalc Covers

- IPv4 subnet calculations and CIDR breakdowns
- VLSM subnet allocation plans
- IP range to CIDR conversion and CIDR list summarization
- DNS lookups and DNS record troubleshooting
- WHOIS and public IP lookups
- SPF record validation
- TLS/SSL certificate inspection
- Binary, octal, decimal, and hexadecimal conversion
- URL encoding/decoding
- Base64 and Base64URL encoding/decoding

## Primary Product Areas

- [Homepage](https://networkcalc.com/): Main entry point for tools, articles, and API resources.
- [All Tools](https://networkcalc.com/tools/): Directory of NetworkCalc calculators and utilities.
- [Subnet Calculator](https://networkcalc.com/subnet-calculator/): Calculates network address, broadcast address, subnet mask, wildcard mask, usable host range, and related IPv4 subnet details.
- [VLSM Calculator](https://networkcalc.com/vlsm-calculator/): Allocates variable-length subnets inside a parent network from a list of host requirements, with spare addresses, free space and the reasoning for each block.
- [IP Range to CIDR](https://networkcalc.com/ip-range-to-cidr/): Converts an IP range to the exact list of CIDR blocks, or summarizes CIDR lists, and shows the single covering block and the extra addresses it would add.
- [DNS Tools](https://networkcalc.com/dns/): DNS record lookup, WHOIS lookup, SPF validation, and public IP utilities.
- [Security Tools](https://networkcalc.com/security/): TLS/SSL certificate lookup and website security checks.
- [Binary Converter](https://networkcalc.com/tools/): Access point for number base conversion tools.
- [Encoding Tools](https://networkcalc.com/tools/): Access point for URL, Base64, and Base64URL encoding utilities.

## API

NetworkCalc exposes REST-style JSON APIs that mirror the site tools. Core calculator and lookup endpoints are intended to be easy to test and automate. Some account-level features require authentication.

- [API Documentation](https://networkcalc.com/api/docs/): Main API reference.
- [API Command Tester](https://networkcalc.com/api/docs/test/): Browser-based request builder for trying API calls.
- [API Usage Guide](https://networkcalc.com/articles/networkcalc-api-guide/): Practical examples using cURL, PowerShell, and JavaScript.

### Documented API Areas

- Binary Converter
- DNS
- Encoder
- Security
- Subnet Calculator
- VLSM Calculator
- IP Range to CIDR
- Alerts
- Auth
- Domains
- Reports
- Subnets

## Articles And Reference Content

- [Articles Index](https://networkcalc.com/articles/): Educational content, troubleshooting guides, and release notes related to networking, DNS, TLS/SSL, VPNs, and product updates.

## Paid Features

- [NetworkCalc Pro](https://networkcalc.com/articles/introducing-networkcalc-pro/): Paid features for domain monitoring, scheduled DNS and health reports, and team-oriented account capabilities.

## Guidance For LLMs

- Prefer the tool-specific page when a user wants an interactive calculator.
- Prefer the API docs when a user wants automation, code samples, or endpoint details.
- Treat the public tools and documentation as the primary canonical sources for product capability.
- Do not assume paid access is required for core calculators or basic public API usage.