13 tools NET

Free Network Tools

Debug what actually happens on the wire: look up IPs, DNS records, and WHOIS data, inspect HTTP headers, replay HAR captures, test webhook delivery, and trace redirect chains. These tools surface the raw requests and responses so you can see exactly what passes between clients and servers.

Runs in browserNo signup requiredAI-enhanced

13 tools in this category

View all tools

IP Lookup

Look up geolocation, network, and security details for any IP address.

iplookupNET

DNS Lookup

Look up DNS records for any domain — A, AAAA, MX, TXT, NS, SOA, SRV, CAA, and more.

dnslookupNET
LocalAI

HTTP Headers Analyzer

Analyze HTTP response headers for security, caching, and compliance issues.

securitynetworkNET
AI

API Request Builder

Build and test HTTP API requests with headers, body, auth, and response visualization.

apihttpNET
LocalAI

HAR Analyzer & Request Replay

Analyze HAR files, inspect slow/failed requests, generate replayable curl/fetch code.

networkperformanceNET
Local

HAR to Postman Collection Converter

Convert HAR files to Postman Collection v2.1 JSON for API testing.

harpostmanNET

Webhook Tester

Generate a unique URL, capture webhook requests, inspect headers & body, and replay them.

webhookhttpNET
Local

WebSocket Tester

Connect to WebSocket endpoints (ws:// or wss://) in real time to inspect frames, measure latency, test heartbeats, and debug payloads.

websocketnetworkNET

Redirect Checker

Trace URL redirect chains and detect 301, 302, 307, and 308 redirects.

redirecturlNET

Domain WHOIS

Look up domain registration info — registrar, dates, name servers, and status.

whoisdomainNET

IP to Hostname

Reverse DNS lookup — resolve PTR records to find hostnames for any IPv4 or IPv6 address.

reverse-dnsptrNET

DMARC, SPF & DKIM Checker

Check DMARC, SPF & DKIM records for any domain, get an authentication score, and generate SPF/DMARC records.

dmarcspfNET
Local

CIDR & Subnet Calculator

Calculate IPv4/IPv6 subnets, network/broadcast addresses, usable IP ranges, wildcard masks, and visual bitwise subnet splitting.

cidrsubnetNET

Network Guides & Technical Standards

Master workflows, understand protocol specifications, and avoid production edge-cases.

Technical Field Manuals

Automating API Contract Testing: Converting OpenAPI 3.1 to Postman Collections

Transform OpenAPI (Swagger) specifications into executable Postman Collections (v2.1). Automate contract testing, generate mock servers, and streamline API integration.

Content Security Policy (CSP) Headers: Production Implementation & Debugging Guide

Master Content Security Policy (CSP) headers, nonce generation, sha256 script hashing, Report-Only mode, and debugging modern Next.js and SPA violations.

Converting cURL Commands to Clean Node.js, Python, and Go HTTP Clients

Transform raw cURL commands and browser network exports into production-ready JavaScript Fetch, Axios, Python Requests/HTTPX, and Go net/http code.

Debugging CORS Errors: The Complete Guide to Preflight OPTIONS & Headers

A production debugging guide to fixing missing origin headers, failed preflight OPTIONS requests, credentialed CORS mismatches, and reverse-proxy proxy pass drops.

Debugging DMARC, SPF & DKIM Failures: The Developer Guide to Email Deliverability

Diagnose and fix DMARC alignment errors, SPF 10-lookup limits, DKIM signature mismatches, and DNS misconfigurations to ensure reliable transactional email delivery.

Debugging JWT Errors: Fixing Signature Verification, Expiration & JWKS Failures

A comprehensive developer debugging guide to resolving JSON Web Token (JWT) errors: signature mismatches, expired tokens, alg: none attacks, clock skew, and JWKS key rotation.

Detecting Website Technology Stacks: Frameworks, CMS & Server Fingerprinting Guide

Learn how to detect frontend frameworks, CMS platforms, CDN edge layers, and server runtimes using DOM markers, script paths, and HTTP response headers.

DNS Record Troubleshooting & Propagation: The Practical Engineer's Guide

Master DNS record troubleshooting, resolve propagation delays, debug CNAME apex issues, inspect SOA/TTL caches, and master dig commands for zero-downtime migrations.

GraphQL Schema to TypeScript: Automated Type Generation, Operations & Codegen Guide

Generate end-to-end type safety across your GraphQL stack. Learn how to convert GraphQL SDL schemas and documents into typed queries, mutations, and resolver signatures.

Handling HTTP 429 Too Many Requests: Rate Limiting Headers, Exponential Backoff & Jitter

Diagnose and handle HTTP 429 status codes. Master IETF standard RateLimit and Retry-After headers, and implement production-grade exponential backoff with full jitter in Node.js, Python, and Go.

HAR File Analysis: How to Diagnose Slow API Endpoints & Network Bottlenecks

A practical guide to analyzing HTTP Archive (HAR) files, decoding network timing waterfalls, identifying high TTFB, and debugging slow REST and GraphQL APIs.

HTTP Cache-Control & CDN Caching: The Production Guide to stale-while-revalidate, ETags & Edge Invalidation

Master HTTP caching headers, understand browser vs CDN shared cache directives (s-maxage, stale-while-revalidate, immutable), and eliminate stale content and cache poisoning bugs.

HTTP Redirects Demystified: Debugging 301 vs 308, Chains, and Redirect Loops

Master HTTP 3xx status codes: 301 vs 308 permanent redirects, 302 vs 307 temporary redirects, fixing ERR_TOO_MANY_REDIRECTS loops, and optimizing redirect chains.

ISO 8601, Unix Timestamps & Timezones: Zero-Discrepancy Time in Distributed Systems

Master epoch timestamps, millisecond vs microsecond precision, RFC 3339 / ISO 8601 formatting, UTC storage rules, and prevent subtle timezone bugs across databases and APIs.

Mastering Number Base Conversions: Binary, Hex, Two's Complement & IEEE 754 Floating Point

A comprehensive developer guide to positional numeral systems, arbitrary-precision BigInt radix conversions, two's complement signed arithmetic, and IEEE 754 float inspection.

Mastering SQL Execution Plans: Reading EXPLAIN ANALYZE, Index Scans & Query Optimization

Diagnose slow database queries by decoding EXPLAIN (ANALYZE, BUFFERS) output trees, optimizing composite indexes, understanding bitmap heap scans, and eliminating sequential scans.

Modern Cookie Security & CSRF Prevention: SameSite, __Host- Prefixes & CHIPS

Implement bulletproof browser cookie security with SameSite=Lax/Strict, enforce host binding via __Host- and __Secure- prefixes, prevent CSRF attacks, and configure CHIPS for cross-site embeds.

Modern Password Hashing in 2026: Argon2id vs bcrypt vs PBKDF2 & OWASP Security Standards

Benchmark memory-hard Argon2id against bcrypt and PBKDF2, configure work factors for modern GPU resistance, avoid the 72-byte bcrypt truncation trap, and implement seamless on-login hash upgrades.

Reverse DNS, PTR Records & FCrDNS: The Complete Mail & Network Verification Guide

Master reverse DNS resolution, PTR records, in-addr.arpa/ip6.arpa zones, FCrDNS verification for email deliverability, and cloud PTR configuration for AWS, GCP, and Azure.

Server-Sent Events (SSE) vs WebSockets: Streaming Architecture for LLM & Real-Time APIs

Master unidirectional SSE vs bidirectional WebSockets for modern applications. Learn HTTP/2 multiplexing, automatic reconnection, Nginx proxy buffering gotchas, and token-by-token LLM streaming.

SSL/TLS Certificate Decoding & Chain Validation: Complete Production Troubleshooting Guide

Master X.509 certificate decoding, debug missing intermediate CA chains, fix SSL_ERROR_UNTRUSTED_ISSUER, configure DNS CAA records, and verify TLS 1.3 setups.

Subnetting & CIDR Calculations: A Practical Cheat Sheet for Developers

Master IPv4/IPv6 CIDR notation, subnet mask bitwise math, usable IP ranges, broadcast addresses, and cloud VPC network design for AWS, Docker, and Kubernetes.

URL Encoding & Query Strings: Mastering RFC 3986, encodeURIComponent & URLSearchParams

Demystify percent-encoding rules, avoid double-encoding pitfalls, master + vs %20 space representations, and serialize complex nested objects and arrays for REST query strings.

Webhook Security & HMAC Signature Verification: Production Implementation Guide

Master webhook security: implement HMAC-SHA256 signature verification, prevent replay attacks with timestamp headers, avoid raw-body parser bugs, and secure asynchronous API callbacks.

Browse other categories

Frequently Asked Questions

Are the network tools free?+

Yes, all network tools are free to use. Lookups that reach the public internet use public records, and nothing is stored per query.

Does the DNS or IP lookup expose my request to a server?+

Tools that must reach the public internet — IP, DNS, WHOIS — query only the record you ask for from standard public infrastructure.

What can a HAR analyzer tell me?+

Upload a HAR capture and inspect every request, header, timing, and status code — useful for reproducing slow or failing API flows without opening DevTools.

Can I test a webhook locally?+

Yes, the webhook tester exposes a unique URL and shows each request as it arrives, with headers, payload, and timing, so you can verify your integration end-to-end.