The goal for this list is a collection of resources and challenges that can be used/done for free, without having to sign up for anything like a mailing list (though you can always use 10 minute mail for the downloads that require an email address). That said, the sites linked will have paid options and/or mailing lists that they would no doubt very much like you to join, so be warned.

Resources

• The KonMari method
• A Slob Comes Clean and how to declutter without making a bigger mess
• UnfuckYourHabitat and UFYH's weekly challenges
• A space for everything - zoning your home and 365 things to declutter from your home and life this year - Organise My House
• [UK only] What can I recycle?
• 120 things to remove from your life - Be More With Less

Challenges

The 30-Day Minimalism Game - The Minimalists
Challenge overview: Starting on the 1st of the month, you declutter a number of items equal to the day of the month. Day 1 = 1 item, Day 2 = 2 items, Day 3 = 3 items etc. for 30 days (or as long as you can keep it up). After 30 days you would have decluttered 465 items. The gentle start eases you into the decluttering and builds as your own ability to recognise what you can declutter improves.

Another popular option is to do it backwards, i.e. Day 1 = 30 items, Day 2 = 29 items, Day 3 = 28 items etc. Some people find this easier as you can get some quick momentum with the initial enthusiasm for the challenge, then as things to declutter become harder to find you don't need to find as many.

Yearly Decluttering Challenge - Nourishing Minimalism
Challenge overview: Over the course of the year, declutter the same number of items as the year, so for 2022 that's a target of 2022 items. Starting on 1st Jan that would be just under 6 items per day.

Nourishing Minimalism encourages you to print off a tally chart* and be flexible with filling in the boxes - if something is particularly difficult to declutter it can count as more than one, if a whole pile of things is too much to count just block off an estimate etc.

*The chart linked in the blog post requires providing an email address, which I assume adds you to their mailing list though I don't specifically remember. I've not had my email address passed to any 3rd parties by Nourishing Minimalism, but it's not hard to come up with your own way to record your progress so likely not worth it if you're not interested in the blog.

The Decluttering Cure - Apartment Therapy
Challenge overview: For 14 days, do their prescribed task, alternating between decluttering a room/category and more abstract "do something that will prevent future clutter" tasks. The idea is to sign up to the mailing list and receive an email with each task, but the link above is to the "catch-up" page which lists them all, saving you from the spam*.
See also: The January Cure for a 20-weekday decluttering/home management challenge starting on 1st Jan and The Holiday Cure for a cleaning-before-Christmas version.

*While I've not had my email address passed to any 3rd parties by Apartment Therapy, they did automatically sign me up to their own mailing list after the January Cure ended. And again after the Decluttering Cure ended, despite having removed myself before. If you're not interested in being signed up for daily emails, don't give them your address.

Decluttering Bursts - Be More With Less
Challenge overview: Grab a trash bag and a donate box and working for 60 minutes find 100 things to get rid of. The linked blog post has suggested item counts from suggested areas for inspiration, and includes digital items in the suggestions.

30 Day Category-Based Challenges

Challenge overview: There are a lot of these. In each case the challenge is to declutter one category each day for 30 days. These often work best if you decide on a period of time to declutter each day (e.g. half an hour) as the categories won't all be similar amounts of effort which could cause burn out on tricky days.

The ones listed here are just those I've found where the category list is freely accessible.

30 Days to Minimalism - Pick up Limes (& video)
The list is in a PDF (no email required) which contains finer descriptions and "tips" on most days. The categories cover both physical and non-physical things, and are individual-focused, no family/pet categories.

30-Day Declutter Challenge - DIY Candy
The list is in a PDF (no email required). The categories in this list are less granular than the Pick up Limes list, and include Pet Supplies and Kid-related days. The linked blog post also lists a number of decluttering approaches with pros/cons, which isn't a bad resource in itself.

30 Day Decluttering Challenge - Simple Lionheart Life
The list is in the linked blog post. Categories are more individual-focused, but the list breaks down some of the potentially larger categories.

30 Day Declutter Challenge - Balance through Simplicity
The list is in the linked blog post. The categories are individual-focused and a mix of physical and non-physical and "instructions" that apply beyond just the day in question. Could be useful for habit-forming.

30 Day Declutter Challenge - List Obsessed
The list is in both the linked blog post and a PDF (no email required). Categories include Kids and jump around various home areas more than some of the others here.