NSDateFormatter — Ben Scheirman
Date string formatter

Save Page Now — Internet Archive
Add pages to the Internet Archive

TinySheet — Postlight
Tiny spreadsheet

TableConvert — FechinLi
Transfrom and convert between table formats

CarefulWords — Simon Sarris
A little bit more than a thesaurus

Yellow Lab Tools — Gaël Métais
Online test to help speeding up web pages

SQLite Viewer — Juraj Novák
Front end for SQLite

Crontab Guru — Cronitor
Editor for cron schedule expressions

Explain Shell — Idan Kamara
Enter shell command and see the help text that matches each argument

JSON Crack — Aykut Saraç
Visualizes JSON data. Herowand Editor visualizes JSON, YAML, XML, TOML and CSV

CanLII — Federation of Law Societies of Canada
Search court judgments, tribunal decisions, statutes and regulations from all Canadian jurisdictions

World Time Buddy — Slava Romanovsky
The best tool to schedule meetings across time zones

Python Tutor — Philip Guo
Visualizing Python, JavaScript, C, C++, and Java programming code execution

BuiltWith — Andrew Rogers & Gary Brewer
Find out what websites are built with

SQLite3 Editor — yy0931
VSCode plugin to edit SQLite3 files like you would spreadsheet applications.

TinEye — Leila Boujnane & Paul Bloore
Reverse image search engine

Twitter Card Preview Tool — Jon Yongfook
Preview Twitter and Facebook cards

Math Trainer
Train mental math

Time.is — Even Scharning
Compare your clock with an atomic clock time and easily see the time across the world

Rectangle — Ryan Hanson
Easily organize macOS windows without using a mouse.

Beast Mode — Namecheap
Bulk domain name search which lets you search 1000+ TLDs with up to 5000 keywords

FontSee
Font viewer to see what OTF, TTF, WOFF, WOFF2 fonts look like

Is My Computer On?
Tool to tell if your computer is on

EmDa.sh
Just an em dash ( — ), so that you can easily copy it when you need an em dash

Twitter Video Downloader
Get the actual CDN link to a video or gif on Twitter

RapidTables Notepad
Online plain text notepad. Great for drafting

Open Parliament — Michael Mulley
A great way to search Canadian parliamentary debates

Canada Income Tax Calculator — Wealthsimple
A simple Canadian income tax calculator based on types of income and RRSP/TFSA contributions

Twitter Publish — Twitter
Quikcly generate Twitter embeds

The Toronto Theatre Database — Canada's Theatre Museum
IMDB for Toronto plays

Elections Ontario Data Explorer — Elections Ontario
Analyze provincial election results in Ontario since 1867

MakeRef — Magnus Manske
Used to help generate Wikipedia reference tags

The On-Line Encyclopedia of Integer Sequences — Neil Sloane
An encyclopedia to lookup integer sequences

HTTP Cats — Rogério Vicente
HTTP Status code guide with cats!

Twitter Profile Page Mockup Generator — Media Modifier
Mockup a Twitter profile page to see how a new profile or banner image looks like

Tax Tips: Combined Tax Rates & Tax Brackets — Boat Harbour Investments
Canadian tax rates & tax brackets with both federal and province income taxes (eg Ontario)

LoopTube — Yuya Uzu
Easily loop all or part of a YouTube video

Real-time HTML Editor — Jesse Ruderman
Easily render HTML snippets

WhatIsMyBrowser — Brett Harris
Get details about your browser, device and operating system settings