Towalles

Token Estimator

Estimate characters, words, and mixed CJK/Latin tokens locally (heuristic, not exact tiktoken)

Prompt Template Filler

Fill {{name}}-style prompt templates from a JSON variable map

LLM Cost Calculator

Estimate API cost from model price table and token counts (static reference prices)

Context Window Checker

See how much of each model's context window your text would use

Chat Messages Formatter

Validate and prettify OpenAI-style messages JSON; export plain-text conversation

JSON Schema from Sample

Infer a simple JSON Schema from sample JSON for structured-output drafts

System Prompt Builder

Assemble role, rules, and examples into one system prompt

Markdown Chunk Splitter

Split long documents by size and overlap for RAG / embedding prep

LLM JSON Extractor

Pull ```json blocks or JSON objects from model replies

Structured Output Validator

Validate JSON against a simple schema locally

Embedding Storage Estimator

Estimate RAM/disk for embedding vectors

API Key Format Checker

Check common LLM API key prefixes locally (no network, no validity check)

PII & Secret Scanner

Scan emails, API keys, JWTs locally

Prompt Redactor

Replace sensitive spans with placeholders

Prompt Diff

Compare two prompt versions

Chat Format Converter

OpenAI to Anthropic/Gemini/plain text

Function Schema Builder

Description

RAG Chunk Analyzer

Chunk size and overlap stats

Context Budget Planner

Multi-slot token budget

LLM Response Cleaner

Strip fences and extra blank lines

ML Eval Calculator

Precision, recall, F1

GGUF Size Estimator

Model file size by quant

Ollama Modelfile Generator

Generate Modelfile

HTML to Text

Strip HTML for RAG and LLM context without sending data upstream

Cryptography

15 tools

Bcrypt Tool

Generate Bcrypt hashes and verify passwords

Hash Generator

Live MD5 and SHA digests with hex or Base64 output and comparison

HMAC Generator

Compute HMAC digests with a secret key (SHA-256 and more)

RSA Key Pair Generator

Generate RSA public/private key pairs in PEM format (browser Web Crypto)

Token Generator

Batch-generate API keys and tokens with crypto-safe randomness

Text Encryption/Decryption

Encrypt and decrypt text locally with AES-GCM and a password

UUID Generator

Batch UUID v4 with multiple formats and compact mode

ULID Generator

Generate sortable, URL-safe unique identifiers

BIP39 Mnemonic Generator

Generate BIP39-compliant English mnemonics

Password Strength Analyzer

Live password complexity scoring and checklist

PDF Signature Checker

Scan a PDF for embedded digital signature markers (client-side heuristic)

OTP Generator

Generate TOTP codes (6–8 digits, Google Authenticator compatible)

Basic Auth Generator

Create or parse HTTP Basic Authorization headers

JWT Decoder

Parse header, payload and signature with expiry warnings; strips Bearer prefix

Password Generator

Generate strong passwords locally with crypto.getRandomValues

Converters

17 tools

Date Time Converter

Convert timestamps and ISO 8601 strings with local, UTC and relative display

Base Converter

Convert between bases 2, 8, 10, 16 and 36 with 0x, 0b, 0o prefixes

Roman Numeral Converter

Convert between Arabic numbers and Roman numerals (1–3999)

Base64 Encoder/Decoder

Live conversion with URL-safe variant and MIME line breaks, full UTF-8

Base64 Image Converter

Encode files to Base64 or decode Base64 to a downloadable file

Color Converter

Convert between HEX, RGB and HSL with live preview

Case Converter

Convert between camelCase, snake_case, kebab-case and more

NATO Phonetic Alphabet Converter

Convert text to NATO phonetic alphabet and back

Text to Binary Converter

Convert text to 8-bit binary and back

Text to Unicode Converter

Convert text to Unicode escapes and back

YAML to JSON Converter

Parse YAML to JSON or format JSON as YAML

YAML to TOML Converter

Convert between YAML and TOML

List Converter

Convert between line lists, CSV, JSON arrays and more

XML to JSON Converter

Convert between XML and JSON

Markdown to HTML Converter

Convert Markdown documents to HTML

IBAN Validator

MOD-97 check

Luhn Checker

Card number checksum

Web Tools

21 tools

URL Encoder/Decoder

Component-level and full URI modes; shows alternate encoding when encoding

HTML Entities Encoder/Decoder

Encode or decode HTML entities (< & ' etc.)

URL Parser

Break down protocol, host, path, query params and hash

Device Information

Inspect browser user agent, screen and hardware hints

Open Graph Meta Tags Generator

Generate og: and Twitter Card meta tags

MIME Types Lookup

Quick reference for common MIME types and extensions

Keycode Info

Live keyboard event key, code and modifier flags

Slugify String

Turn titles or paths into URL-friendly slugs

HTML Editor

Edit HTML and preview rendered output in the browser

HTTP Status Codes

Quick reference for common HTTP status codes

JSON Diff

Compare two JSON documents and list added, removed and changed fields

Safelink Decoder

Extract real URLs from Google, Outlook and similar safe links

Email Normalizer

Normalize emails: lowercase, strip Gmail dots and + tags

CSP Builder

Build CSP header

SRI Generator

sha384 integrity hash

Semver Calculator

Bump and compare versions

robots.txt Generator

Crawler rules

UTM Builder

Campaign tracking URLs

Meta Length Checker

Description

Color Contrast Checker

Check foreground/background contrast against WCAG

User-Agent Parser

Parse browser, OS, and device from a UA string

Media Tools

11 tools

QR Code Generator

Generate PNG QR codes from URLs or text with ECC and size options

WiFi QR Code Generator

Generate QR codes to join a WiFi network

SVG Placeholder Generator

Generate SVG placeholders and Data URLs for mockups

Image Compressor

Compress JPEG images in the browser with optional max width

Image Cropper

Crop images by percentage region (x, y, width, height)

Image Converter

Convert between PNG, JPEG and WebP

Image Information Viewer

Read photo EXIF metadata locally — nothing is uploaded

Image Grid Splitter

Split an image into a row/column grid (up to 9×9)

Color Palette Extractor

Dominant colors from image

Favicon Generator

Multi-size PNG icons

Audio Metadata Viewer

Duration and MIME

Development Tools

23 tools

Git Command Reference

Quick reference for common Git commands

Random Port Generator

Generate unique random ports in a range

Crontab Generator

Build cron expressions and crontab lines visually

JSON Formatter

Format, validate and minify JSON with customizable indentation

JSON to CSV Converter

Export JSON arrays or objects as CSV

SQL Formatter

Format SQL with uppercase keywords and indentation

CHMOD Calculator

Toggle permissions or enter octal/symbolic modes with live conversion

Docker Run to Docker Compose

Convert docker run commands to docker-compose.yml snippets

XML Formatter

Format or minify XML documents

YAML Formatter

Format or minify YAML documents

Regular Expression Tester

Live matching, capture groups and replace preview

Regular Expression Memo

Quick reference for regex syntax and examples

Env Diff

Compare .env files

OpenAPI Formatter

Pretty-print and lint shape

GraphQL Formatter

Indent GraphQL queries

JSONPath Tester

Run JSONPath on JSON

JMESPath Tester

Simple JMESPath expressions

License Header Generator

MIT/Apache/BSD headers

XPath Tester

XPath on XML

WireMock Stub Generator

Generate stub JSON

CSV Dedupe

Dedupe rows by column

Nginx Config Generator

Reverse proxy snippet

Mock JSON Generator

Batch-generate test JSON from a template for APIs and frontends

Network Tools

14 tools

IPv4 Subnet Calculator

Compute network, broadcast and host counts from CIDR

IPv4 Address Converter

Convert dotted decimal to integer, hex and binary

IPv4 Range Expander

Expand CIDR or start–end IP into a list (max 1024 addresses)

MAC Address Lookup

Look up common vendors by OUI prefix (offline database)

MAC Address Generator

Generate random MAC addresses in bulk

IPv6 ULA Generator

Generate RFC 4193 local unique /48 ULA prefixes

IPv6 Subnet Calculator

Compute IPv6 network range from CIDR notation

Network Unit Converter

Convert bits, bytes and SI/binary prefixed units

IPv6 Address Converter

Expand and compress IPv6 addresses

VLSM Calculator

Variable-length subnet masking for IPv4 networks

CIDR Aggregator

Summarize multiple IPv4 CIDR blocks into a covering prefix

ACL Generator

Generate Cisco-style extended access-list rules

VLAN Calculator

Split a base IPv4 network into VLAN subnets

VLAN Generator

Generate random VLAN IDs and Cisco-style VLAN config snippets

Math Tools

11 tools

Math Calculator

Evaluate basic arithmetic expressions

ETA Calculator

Estimate remaining time and finish time from progress

Percentage Calculator

What percent, percent of, and percent increase/decrease

Unit Converter

Convert area, volume and speed units

Finance Calculator

Compound interest and loan payment estimates

Geometry Calculator

Area of circles, rectangles and triangles

Random Generator

Crypto-safe random integers or floats in a range

Fraction Calculator

Add, subtract, multiply and divide fractions with simplification

Base Converter

Convert between bases 2, 8, 10, 16 and 36 with 0x, 0b, 0o prefixes

Statistics Calculator

Mean, median, standard deviation and more

Trigonometry Calculator

Compute sin, cos and tan from degrees

Measurement

7 tools

Timer

Stopwatch and countdown with pause and reset

Temperature Converter

Convert between Celsius, Fahrenheit and Kelvin

Benchmark Generator

Run a simple array-sum benchmark in the browser

Length Converter

Convert between meters, km, inches, miles and more

Weight Converter

Convert between kg, g, lb, oz and more

Time Converter

Convert ms, seconds, minutes, hours, days and weeks

World Clock

Current time across time zones

Text Tools

7 tools

Lorem Ipsum Generator

Placeholder paragraphs with configurable structure

Text Analyzer

Live counts for characters, words, lines, paragraphs and UTF-8 bytes

Emoji Picker

Browse common emoji and copy with one click

String Obfuscator

Simple encode/decode: Base64, Hex, ROT13 and more

ASCII Art Text Generator

Render A–Z and 0–9 as block letter banner text

Text Diff Checker

Line-by-line text comparison with add/remove highlighting

Readability Scorer

Heuristic readability