Free Security & Crypto Tools & Calculators
Browse 40+ free interactive security & crypto calculators, estimators, and utilities. 100% free, private, and runs directly in your browser without signup.
AES Encryptor — AES-256 Text File Encryption Online (Free, GCM)
Free online AES-256 encryptor. Encrypt text and files with AES-256-GCM (authenticated) or OpenSSL-compatible AES-256-CBC, PBKDF2 key derivation, random salt per file. 100% client-side — nothing ever leaves your browser.
Ascii85 Encoder - Adobe, RFC 1924 & Z85
Free online Ascii85 encoder with three variants: Adobe Ascii85, RFC 1924 Base85, and ZeroMQ Z85. Text, file, or hex input; 100% client-side.
Bcrypt Validator & Hash Inspector
Real-time Bcrypt hash syntax validator, cost factor analyzer, and modular crypt format diagnostic tool.
BIP39 Seed Phrase Generator & Mnemonic Validator
Free BIP39 mnemonic generator: create 12-24 word seed phrases with secure randomness, validate checksums, derive 512-bit seeds. 100% client-side.
Classical Cipher Lab — Caesar, ROT13 & Vigenère Decoder/Encoder Online
Free online classical cipher lab: ROT13/ROT5/ROT47 encoder-decoder, Caesar cipher encoder/decoder with 26-shift brute-force solver and frequency analysis, Vigenère encoder/decoder with key-length estimation and chi-square key recovery, plus an interactive tabula recta. 100% client-side — nothing ever leaves your browser.
Corrected Magnesium Calculator — Albumin-Adjusted Mg (Educational)
Educational calculator comparing measured serum magnesium with an albumin-adjusted estimate from published literature. No universal clinical standard
CSP Generator — Free Content Security Policy Header Generator (Online)
Generate a Content Security Policy (CSP) header online: visual directive builder, nonce & SHA-256/384/512 hash generator, CSP validator, and copy-paste presets for WordPress, nginx, Apache, IIS, Express & Laravel. Free, no signup, runs 100% in your browser.
CVSS Calculator — v4.0, v3.1, v3.0 v2.0 Score Calculator (Free, Client-Side)
Free CVSS calculator for all versions — v4.0, v3.1, v3.0 and v2.0 — on one page. Paste a CVSS vector string or click metrics to get the base, temporal and environmental scores instantly. 100% client-side: nothing leaves your browser.
DNS WebRTC Leak Test — Check for IP, DNS IPv6 Leaks (Free)
Free DNS & WebRTC leak test. Find out if WebRTC exposes your real IP address, detect IPv6 leaks, and learn exactly what a DNS leak test can and cannot check. Runs in your browser — no signup.
DSA Key Generator
Free online DSA key generator. Generate DSA key pairs (1024/2048-bit) with p/q/g domain parameters, PEM export, and RFC 6979 sign/verify testing. 100% client-side.
SPF, DKIM DMARC Generator — Free Email Authentication Studio (3-in-1)
Free 3-in-1 email authentication studio: SPF record generator with 10-lookup-limit simulator, real DKIM key-pair generator (RSA via WebCrypto), and DMARC record builder with RFC 9989 (DMARCbis) support. 100% client-side — your domain data never leaves your browser.
Email Header Analyzer — Check SPF, DKIM, DMARC & Detect Phishing (Free)
Free online email header analyzer. Paste raw email headers to check SPF, DKIM & DMARC authentication, trace the Received chain hop by hop, and detect phishing & email spoofing. 100% client-side — your headers never leave your browser.
Enigma Machine Simulator (M3) — Free Online Enigma Encoder & Decoder
Free online Enigma M3 machine simulator: historically accurate rotors I–VIII, ring settings, plugboard and double-stepping, with live signal-path visualization. Encrypt & decrypt Enigma messages in your browser — no data leaves your device.
FEV1/FVC Ratio Calculator — GOLD Interpretation + NHANES III % Predicted
Calculate the FEV1/FVC ratio from spirometry: GOLD criteria interpretation (< 0.70), % predicted & LLN via NHANES III reference equations, and GOLD severity grades 1–4. Free, 100% client-side.
File Checksum Verifier — Verify MD5, SHA-1, SHA-256, SHA-512 SHA3 Online (Free)
Free online file checksum verifier. Drag & drop any file to compute MD5, SHA-1, SHA-256, SHA-384, SHA-512 and SHA3-256 in one pass — compare against expected hashes or verify whole .sha256sum files. 100% client-side: your files never leave your browser.
Fisher Equation Calculator — Nominal, Real & Inflation Solver
Fisher Equation Calculator: compute nominal, real, and inflation rates with the exact formula (1+i)=(1+r)(1+π), compare with the approximation, scenario table, and purchasing power calculator. Free and educational.
Hammock Stand Size Calculator — Stand Length, Weight Capacity & Hang Angle (Free)
Free hammock stand size calculator: stand length, weight capacity, 30-degree hang angle, footprint planner and cost estimator. Private, in your browser.
Hash Identifier Online — Identify MD5, SHA256, bcrypt & 300+ Hash Types (Free)
Free online hash identifier. Paste any hash to instantly identify MD5, SHA1, SHA256, SHA512, bcrypt, NTLM, WordPress, Django & 300+ hash types. 100% client-side — your hashes never leave your browser. No signup.
HTML Sanitize Tester — Test HTML Sanitization Online (Free)
Test your HTML sanitizer online: paste markup, see which tags survive an allowlist filter — script, on*, javascript: URLs stripped. Free tool.
Image Morse Code Translator
Full morse code translator — audio, text, image/picture to morse code, morse code into english, decode morse audio, morse sound decoder, morse code copy paste, and more.
MD2 Generator — Free Online MD2 Hash Generator (RFC 1319)
Generate MD2 hashes from text or files entirely in your browser. Pure-JavaScript RFC 1319 implementation, batch mode, HMAC-MD2, uppercase/lowercase hex, and self-verifying test vectors. 100% client-side.
MD4 Generator — Free Online MD4 Hash Generator (RFC 1320)
Generate MD4 hashes from text or files entirely in your browser. Pure-JavaScript RFC 1320 implementation, batch mode, NTLM, HMAC-MD4, base64 output, and self-verifying test vectors. 100% client-side.
Meat Carbon Footprint Calculator — How Much CO₂ Does Your Meat Habit Produce?
Free meat carbon footprint calculator: enter how much beef, lamb, pork, chicken, turkey, fish, dairy and eggs you eat to get your annual CO₂e, car-mile equivalents, and what-if swap scenarios. 100% private, runs in your browser.
Mirror Equation Calculator — Solve f, do, di, M
4-way mirror equation calculator: compute focal length (f), object distance (do), image distance (di), or object height (ho). Automatic image classification (real/virtual, upright/inverted, magnified/reduced) + SVG ray diagram.
Nursery Size Calculator — 7 Ways to Plan the Perfect Nursery Room
Nursery size calculator: crib footprint + 36-inch clearance, 10x10 room rule, glider recline space, changing table zones and toddler-bed growth plan.
Passphrase Generator — Free Diceware Passphrase Generator (EFF Wordlist, Real Entropy)
Free diceware passphrase generator: memorable, high-entropy passphrases from the EFF wordlist (7776 words), picked with a bias-free CSPRNG. Real entropy calculation, crack-time estimates, physical-dice mode. 100% client-side — nothing leaves your browser.
Password Entropy Calculator — Bits of Entropy + Crack Time Estimates
Free password entropy calculator: measure password strength in bits (L × log2(N)), get honest crack-time estimates across 4 attack scenarios, charset presets, diceware passphrase entropy, and worked examples. 100% client-side — your password never leaves your device.
Password Strength Checker — How Secure Is My Password?
Free password strength checker: instant 0–100 score with label, crack-time estimates across 3 attack scenarios, keyboard-walk and common-password detection (including leetspeak variants), specific improvement tips, and a transparent score breakdown. 100% client-side — your password never leaves your browser.
Retirement Savings Calculator — 401(k), IRA, Roth vs Traditional & Social Security | nrtechstudio.com
Free retirement savings calculator with GOAT depth: savings projector, 401(k) employer-match optimizer with 2026 IRS limits, Roth vs Traditional comparator, 4% rule readiness check, Social Security bridge & catch-up planner. 100% private, runs in your browser.
Standalone - RIPEMD-160 Generator
Generate RIPEMD-160 cryptographic hashes.
SRI Hash Generator — Free Subresource Integrity Hash Generator (SHA-256/384/512)
Generate SRI integrity hashes online: SHA-256, SHA-384 and SHA-512 computed at once from text, files, or a URL. Snippet builder for <script> and <link> tags, verify mode, and a troubleshooting guide for failed integrity checks. Free, no signup, 100% client-side.
SSH Key Fingerprint Checker — MD5 & SHA256 Fingerprints + Randomart (Free)
Free SSH key fingerprint checker. Paste a public key to get MD5 & SHA256 fingerprints exactly like ssh-keygen -lf, visual randomart, and verify GitHub, GitLab & Bitbucket host keys. 100% client-side — keys never leave your browser.
SSL Certificate Decoder — Decode X.509, CSR & Check Private Key Match (Free)
Free SSL certificate decoder. Paste a PEM certificate to decode every X.509 field — subject, issuer, SAN, expiry, key usage, fingerprints. Also decodes CSRs and checks private-key match. 100% client-side — nothing is uploaded.
Thin Lens Equation Calculator: Solve f, do, di, M
4-way thin lens equation calculator: solve focal length (f), object distance
TOTP Generator — Free 2FA Code Generator Online (SHA-1/SHA-256/SHA-512 + Validator)
Free online TOTP generator: create time-based one-time passwords (2FA codes) in your browser. SHA-1, SHA-256, SHA-512, 6/8 digits, live countdown, code validator, otpauth:// import. 100% client-side — your secret never leaves your device.
VBAC Risk Score Calculator (Grobman 2007 & 2021) — Probability of Successful Vaginal Birth After Cesarean — NR Tech Studio
VBAC success probability calculator using the Grobman 2007 model and the 2021 race-free update (SMFM): age, BMI, vaginal/VBAC birth history, recurring cesarean indication, chronic hypertension. With per-factor explanations, risk categories, VBAC vs repeat cesarean comparison, contraindication checklist, and FAQ. Educational tool — not medical advice.
Vegan Carbon Footprint Calculator — Diet CO2e vs Omnivore, Vegetarian, Pescatarian
Free vegan carbon footprint calculator: enter your weekly plant-food consumption and see your diet
Predicted Vital Capacity (VC) Calculator — Baldwin, ECSC & NHANES III
Calculate predicted vital capacity (VC) from height, age, and sex using three verified reference equations: Baldwin 1948, ECSC 1993, and NHANES III 1999. Includes % predicted, LLN, interpretation, reference tables, and a trend logger.
Standalone - Whirlpool Generator
Generate Whirlpool 512-bit hashes.
AutoSAST — Free SAST & Code Security Scanner | NR Tech Studio
Free online SAST code security scanner. Audit ZIP archives & GitHub repos for OWASP Top 10:2021 flaws using Semgrep AST and instant AI fix patches.
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How to Use the Tools Directory
Every tool is a single interactive page: enter your inputs, get instant results, no account needed. Use the search box (shortcut: press /) to jump straight to a tool, or browse categories when you are exploring. Each card links to the tool's permanent URL, which you can bookmark or share.
Because all computation happens in your browser, the tools are fast, private, and free forever. If a result looks wrong, use the one-click report control on the tool page so it can be fixed.
Tool Categories at a Glance
| Category | What you will find | Example tasks |
|---|---|---|
| Developer | Encoders, formatters, regex, network tools | Format JSON, test regex, subnet a network |
| Finance | Tax, loans, salary, investing | Estimate tax brackets, amortize a loan |
| Home improvement | Estimators, measurements, materials | Size a wire, estimate paint or flooring |
| Health & fitness | Body metrics, nutrition, workouts | Track BMI, plan calories, score fitness tests |
| Math & science | Converters, geometry, statistics | Convert units, solve triangles |
| Text | Counters, sorters, generators | Count words, alphabetize a list |
| Color | Pickers, converters, checkers | Convert HEX to RGB, check contrast |
| Everyday life | Cooking, travel, automotive, pets | Convert recipes, plan fuel costs |
Popular Tasks and Where to Start
| I want to... | Start with | Why |
|---|---|---|
| Convert between number bases | Binary Converter | Step-by-step base conversion with charts |
| Validate and format data | JSON Formatter | Pretty-print and check JSON instantly |
| Count words for an essay | Word Counter | Words, characters, reading time |
| Check password strength | Password Strength Meter | Entropy-based strength scoring |
| Grade text readability | Readability Score | Flesch-Kincaid and grade levels |
| Audit color contrast | Accessibility Checker | WCAG contrast ratios in one click |
Tools Directory FAQ
What is the NRTechStudio tools directory?
It is a free catalog of more than 2,700 interactive web tools: calculators, converters, generators, and checkers for developers, finance, home improvement, health, education, and everyday tasks.
Are all the tools really free?
Yes. Every tool in the directory is free to use with no sign-up, no trial, and no paywall. They run entirely in your browser.
Do I need to create an account?
No. There are no accounts, logins, or subscriptions. Open a tool and use it immediately.
Is my data private when I use these tools?
Yes. The tools are 100% client-side: your inputs are processed by JavaScript in your own browser and never sent to a server.
How do I find the right tool?
Use the search box at the top of the directory (press / to focus it), or browse by category. Every tool card shows a short description of what it computes.
Do the tools work on mobile?
Yes. The directory and the tools use responsive layouts that adapt to phones, tablets, and desktops.
How many tools are there?
The directory holds more than 2,700 tools and grows regularly as new calculators and converters are published.
Can I request a new tool?
Yes. Each tool page has a report/feedback control you can use to request features or new tools; requests help prioritize what gets built next.
Are the tools accurate?
Calculators use published formulas and reference data (tax tables, NEC ampacity, standard conversions). Each tool page documents its method, and issues can be reported in one click for a fix.
Do tools work offline?
Once a tool page has loaded, most tools keep working without a connection because the logic is client-side JavaScript. The directory search needs the page loaded first.
What categories are covered?
Developer utilities, finance and tax, home improvement, health and fitness, math and science, text tools, color tools, networking, education, and everyday life calculators, among others.
Can I bookmark or share a tool?
Yes. Every tool has its own permanent URL under nrtechstudio.com/tools/, which you can bookmark or share directly.
Is there an API for these tools?
The tools are interactive web pages, not API endpoints. The underlying math is plain JavaScript you can inspect in the page source.
Why do some tools show ratings?
Ratings aggregate user feedback to surface the most trusted tools and flag pages that need fixes or better explanations.
How often are new tools added?
New tools are published on a continuous pipeline, prioritized by measured search demand and by user requests from the feedback controls.
Who builds these tools?
NRTechStudio, an independent tools studio focused on free, private, client-side utilities that respect user privacy.