UD5 Toolkit
DKIM Record Generator - Online Public Key DNS Entry
Generate a DKIM DNS record from a public key and selector. Check syntax. Improve your domain’s email deliverability.
Email Header Parser - Online Analyze Email Delivery Path
Email Header Analyzer
Paste the full email header below to trace the delivery path and check authentication status.
Frequently Asked Questions
An email header is the hidden part of an email containing technical details like sender and recipient addresses, subject, date, and the path the email took across mail servers. It helps diagnose delivery issues and detect spam or phishing.
Gmail: Open the email, click the three dots (More) > Show original.
Outlook: Double-click the email > File > Properties, then look under Internet headers.
Yahoo: Open the email, click More > View Raw Message.
Apple Mail: Open the email, go to View > Message > Raw Source.
Outlook: Double-click the email > File > Properties, then look under Internet headers.
Yahoo: Open the email, click More > View Raw Message.
Apple Mail: Open the email, go to View > Message > Raw Source.
Each "Received" line is added by a mail server as the email passes through it. The topmost Received header is added by the final server (recipient's), and the bottommost is from the original sender. By reading them in reverse order you can trace the exact delivery path.
SPF (Sender Policy Framework) checks that the sending server's IP is authorized to send emails for the domain. A "pass" result means the IP is allowed; "fail" often leads to spam filtering.
DKIM (DomainKeys Identified Mail) adds a digital signature to the email, verifying that the message hasn't been modified and truly comes from the claimed domain. It helps prevent email spoofing.
DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds on SPF and DKIM. It tells receiving servers what to do if authentication fails (reject/quarantine/none) and provides reporting on who is sending emails from your domain.
Common reasons include missing or failed SPF/DKIM/DMARC, blacklisted IP, unusual sending patterns, or content that triggers spam filters. Use this analyzer to check if authentication passed and trace the server path.
Blob URL Generator - Online Create Temporary Object URL
Create a Blob from text or a file and generate a temporary URL for it. Understand the Blob API. Dev demo.
Video to GIF Converter - Online Create Animated Images
Trim a video clip and convert it into an animated GIF. Adjust frame rate and size. Processing stays on your computer for privacy.
High Quality Video to GIF - Online Optimized Converter
Convert short video clips to GIFs with adjustable resolution, frame rate, and dithering. Preview before download. All local.
Image to Markdown Base64 - Online Embed Small Pics
Convert a small image into a Base64 data URI and get a Markdown image tag. Perfect for README files and note‑taking apps. Local.
Random Git Commit Message Generator - Online Fun
Generate a humorous, realistic‑looking git commit message. Perfect for testing or filling mock repos.
HTML Symbol Entities Cheatsheet - Online Search & Copy
Search and copy HTML entities for arrows, math, currency, and symbols. See the glyph and code. Fast reference.
Animated GIF to WebP Converter - Online Smaller Size
Convert animated GIFs to animated WebP format for smaller file size. Choose quality level. All processing in browser.
GIF Reverse Tool - Online Create Backwards Animated GIF
Upload an animated GIF and generate a reversed version. Share the funny backwards motion. Works entirely in your browser via canvas.
Dynamic SVG Placeholder Generator - Online Text-Based
Generate an SVG placeholder image with custom text, width, height, and colors. Use as a placeholder service. Pure SVG.
Wood Joint Selector – Online Choose Based on Load & Look
Answer questions about project type and strength needed to get a joint recommendation. Animations.
Saponification Value Lookup – Online Oils & Butters
Search for the NaOH and KOH sap values of various oils. Reference for cold process soap makers.
Star Trail Length Calculator – Online 500 Rule & More
Calculate maximum shutter speed before star trailing (NPF rule) and estimate trail length for creative effects.
CSS Animation Generator - Online Keyframes & Transitions
Create CSS animations and transitions without coding. Define keyframes, easing, and duration. Copy the @keyframes and animation code instantly.
JavaScript Regex Cheatsheet - Online Interactive Pattern Reference
Interactive cheatsheet for JavaScript regular expressions with live examples. Click any token to see its explanation and test it on sample text immediately.
HTTP Methods Cheatsheet - Online GET POST PUT DELETE Guide
Quick reference of HTTP methods with their semantics, idempotency, and example REST usage. Static, fast.
Emoji Background Pattern Generator - Online Repeat CSS
Select emojis and arrange them into a seamless tiling background. Copy the CSS data‑URI or download as image.
Markdown Table Generator - Online Visual Builder & Formatter
Create and format Markdown tables by adjusting rows and columns. Align text, copy the raw Markdown. Perfect for README files.
Paper Size Visual Comparison – Online A4 vs Letter vs Legal
Overlay outlines of different paper sizes scaled to real dimensions on screen. Choose the right one.
Moving Truck Size Calculator – Online Bedrooms to Cubic Feet
Enter number of bedrooms and large items to estimate the truck size you need. Avoid multiple trips. Simple local estimator.
CSS Transform Origin Playground - Online Visual Pivot
Click on a box to set the transform‑origin point and see how rotations and scales change. Copy the CSS.
Horror Movie Title Generator – Online Spooky Name Creator
Create random spooky film titles with adjectives, nouns, and years. Perfect for Halloween or writing prompts.
.nvmrc Node Version Generator - Online
Select a Node.js version from the LTS list and instantly download a .nvmrc file. Lock your project’s runtime.
Babel Config Generator - Online Presets & Plugins
Choose Babel presets (env, React, TypeScript) and plugins. Get a clean babel.config.json to transpile your code. Local tool.
Tree Planting Offset Calculator – Online How Many Trees to Neutralize Flight
Enter flight distance to see estimated CO2 emissions and how many trees it would take to absorb that over 10 years.
Chess Board Viewer - Online Setup FEN & Analyze Positions
Set up a chess position using FEN notation or drag pieces. Share the position link or screenshot. No AI, just board.
5-4-3-2-1 Grounding Exercise – Online Anxiety Relief
Guided sensory grounding exercise with prompts for sight, touch, hearing, smell, taste. Interactive and calming.
Fire Extinguisher Selector – Online Class A B C D K Guide
Choose the right extinguisher for kitchen, electrical, or garage fires. Interactive class chart. Home safety education.
Virtual Circular Slide Rule – Online E6B Style Calculator
Drag the virtual ring to perform multiplication, division, and unit conversions. Rediscover pre‑electronic calculator charm.
Stick Welding Rod Selector – Online Material & Position Guide
Choose base metal thickness and welding position to get the right rod diameter and amperage range. Beginner welder's quick reference.