Network & API Tools
11 toolsNetwork debugging and API development are core tasks for backend developers, DevOps engineers, and security professionals. Whether you are calculating subnet ranges for infrastructure planning, looking up DNS records to troubleshoot domain resolution, analyzing HTTP response headers for security misconfigurations, converting cURL commands to production code, testing webhook integrations, or verifying SSL certificate validity — these tasks require precise tools that give instant answers. These browser-based utilities handle the most common network and API operations developers face daily: calculate IPv4 subnets with CIDR notation including network address, broadcast, host range, and usable host count; query DNS records (A, AAAA, MX, CNAME, TXT, NS) using DNS over HTTPS for privacy; analyze HTTP response headers for security best practices and missing protections; convert cURL commands to JavaScript, Python, Go, PHP, and Node.js code; build and parse webhook payloads for integration testing; and check SSL certificate details including issuer, validity, and chain information. All tools run entirely in your browser with no data sent to external servers unless explicitly required for the lookup (DNS and SSL queries use public APIs).
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Search all tools insteadCommon Use Cases
Calculate IP subnet ranges and CIDR blocks for network infrastructure planning
Look up DNS records to troubleshoot domain resolution and email delivery issues
Analyze HTTP response headers to identify security vulnerabilities and missing protections
Convert cURL commands from API documentation into production-ready code in any language
Build and validate webhook payloads for third-party service integrations
Verify SSL certificate validity, expiration dates, and certificate chain details
Debug API requests by inspecting headers, status codes, and response metadata
Frequently Asked Questions
Do these tools send my data to external servers?
Most tools run entirely in your browser. DNS Lookup uses public DNS over HTTPS (DoH) endpoints (Google or Cloudflare) to resolve domain names — only the domain you query is sent to the DoH provider. SSL Certificate Checker provides educational analysis and best practices. All other tools (IP calculator, cURL converter, HTTP header analyzer, webhook tester) process data locally without any network requests.
Can I use the IP Subnet Calculator for IPv6 addresses?
The current version focuses on IPv4 subnet calculations with full CIDR support. IPv4 remains the most commonly used addressing scheme for subnet planning and network segmentation tasks. IPv6 support may be added in future updates.
What DNS record types can I look up?
The DNS Lookup tool supports all common record types: A (IPv4 address), AAAA (IPv6 address), MX (mail exchange), CNAME (canonical name alias), TXT (text records including SPF and DKIM), and NS (nameserver). These cover the vast majority of DNS troubleshooting scenarios.
Which programming languages does the cURL converter support?
The cURL to Code converter supports JavaScript (fetch API), Python (requests library), Go (net/http), PHP (cURL extension), and Node.js (node-fetch/https). Each output includes proper error handling and follows the idiomatic patterns of the target language.
How does the HTTP Header Analyzer score security?
The analyzer checks for the presence and correct configuration of security-related headers: Content-Security-Policy, Strict-Transport-Security (HSTS), X-Content-Type-Options, X-Frame-Options, Referrer-Policy, and Permissions-Policy. Each header is evaluated against current best practices, and the overall score reflects how many recommended security headers are properly configured.
Can the Webhook Tester receive real webhook requests?
The Webhook Tester operates in client-side simulation mode — it helps you build, format, and validate webhook payloads without requiring a real server endpoint. For receiving actual webhook requests, you would need a server-based solution. This tool focuses on payload construction, JSON validation, and format verification.
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