Security tools for developers and analysts

Security utilities, in your browser.

Hashing, HMAC, encryption, TOTP, password and breach checks, DNS and email security, certificate decoding and network diagnostics. Client-side first — nothing is stored.

Passwords

⏱

Password Strength Checker

Estimate password entropy and risk

⚠

Password Breach Check (HIBP)

Check if a password appears in data breaches

Hashing & MAC

HM

HMAC Generator

Compute HMAC-SHA signatures

Σ

File Checksum Calculator

Compute SHA-1, SHA-256 or MD5 of a file

?

Hash Identifier

Identify the algorithm behind a hash

⛏

Dictionary Hash Cracker

Brute-force hashes against a wordlist

Encryption

🔒

AES Encrypt / Decrypt

Encrypt text with AES-256-GCM locally

🗝

RSA / EC Keypair Generator

Generate RSA, EC and Ed25519 keys

📦

Encrypt / Decrypt a File

AES-256-GCM encrypt any file locally

Tokens & 2FA

6

TOTP / HOTP Generator

Generate time-based one-time passwords

◇

Random Token Generator

Generate API keys and random tokens

Certificates

🛡

Certificate Decoder

Parse and decode X.509 certificates

SSH

SSH Key Fingerprint Checker

Compute SSH public key fingerprints

Network & DNS

DNS

DNS Lookup

Query DNS records for any domain

≡

DNS Propagation Checker

Compare DNS records across resolvers

ID

WHOIS Lookup

Look up domain and IP registration data

◧

Subnet Calculator

Calculate IPv4 and IPv6 subnets

▤

MAC Address Lookup

Find the vendor behind a MAC address

IP

IP Address Info

See your IP, ISP, ASN and geo location

▣

Security Headers Cheat Sheet

Reference for HTTP security headers

⇅

Common TCP/UDP Ports

Reference table of well-known ports

⇅

Port Scanner

TCP port connectivity scan

⌁

Subdomain Finder

Enumerate subdomains via CT logs

✓

DNSSEC Checker

Check DNSSEC validation for a domain

Email Security

✉

SPF / DKIM / DMARC Check

Check and explain email authentication

⚙

SPF / DMARC Record Generator

Build SPF, DMARC and DKIM records

Web Security

⚠

OWASP Top 10 Reference

The 10 most critical web app risks

API

OWASP API Security Top 10

The 10 most critical API security risks

⊞

Security Header Scanner

Live-grade any URL’s security headers

↳

Redirect Checker

Follow and inspect redirect chains

Ciphers & Analysis

?

Cipher Tools (Caesar, XOR, Vigenère)

Encode and decode classic ciphers

∿

Entropy Calculator

Measure the randomness of text or a file

Frequently asked questions

What is checksec?

A collection of free, browser-first security utilities — hashing, HMAC, encryption, TOTP, password and breach checks, DNS and email security, certificate decoding and network diagnostics — aimed at developers and security analysts.

Are my passwords and files safe here?

Yes. Most tools run entirely in your browser using the Web Crypto API, so passwords, keys and files never leave your device. Nothing is stored, and we never see the data you enter.

Which tools make a network request?

Lookups and live checks — DNS, WHOIS, email security, IP info, MAC lookup, password-breach, security-header scanning, port scanning, subdomain finding, redirect tracing and DNSSEC — fetch live public data. Each of these pages states explicitly that it makes a network call.

Do you store or log my data?

No. Tools that run in the browser never send your input anywhere. Network tools query trusted public APIs (HIBP, Cloudflare DNS, ipwho.is, etc.) without logging your data on our side, and nothing is stored in cookies beyond your theme preference.

Are these tools free to use?

Yes. All tools are free and advertisements are not the point of the site. They generate nothing that requires payment or accounts.