Recently, I've been really into collecting self defense items! Here are my findings, maybe it can help someone. It's sad that we need to resort to this, but since these tools are available, we might as well take advantage of them:

Swiss Army Hunter Pro Pocket Folding Knife

https://www.swissarmy.com/us/en/Products/Swiss-Army-Knives/Outdoor/Hunter-Pro/p/0.9411.M3

I'm an avid knife collector and have explored multiple brands and knife types including opinel, benchmade, buck, etc.etc., but I like this knife the most, in terms of convenient self defense. It doesn't take up that much space when folded, but when you deploy the knife it is quite big, large enough to defend yourself. It has a locking mechanism for safety and the quality of the blade is amazing. It's very discreet.

Here are some things I keep on my keys / keychain:

-Car window breaker keychain

https://www.amazon.com/dp/B01G6C18EC/ref=redir_mobile_desktop?_encoding=UTF8&aaxitk=81d2e0b7eb1eb83ca5fc50d2ed7cb69a&hsa_cr_id=3206802440801&pd_rd_plhdr=t&pd_rd_r=6923e2a3-2159-490b-a08b-b3e646ecb072&pd_rd_w=EyUDv&pd_rd_wg=H4e8s&ref_=sbx_be_s_sparkle_mcd_asin_0_img

-Pepper spray

https://www.amazon.com/SABRE-3-1-Pepper-Spray/dp/B005CMZYQQ/ref=sr_1_4_sspa?keywords=sabre%2Bpepper%2Bspray&qid=1637945631&sr=8-4-spons&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExNFJRRkFTRU5DRlROJmVuY3J5cHRlZElkPUEwODU1MTMxMVhHWDA3TDg1MDY1UCZlbmNyeXB0ZWRBZElkPUEwNTI5NjU3SlIyMjRXQjVFVkcyJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1

-Self defense spikes (better to use than your keys, in portable sizes)

https://www.instagram.com/mystifyingdefense/?hl=en

Some additional things that might be useful to carry around as well:

Portable door lock

https://www.amazon.com/dp/B08L7DNXT9?pd_rd_i=B08L7DNXT9&pd_rd_w=mpBAO&pf_rd_p=7ea8e9d0-fed1-49e8-a002-f2d3f5cb151d&pd_rd_wg=8pWXW&pf_rd_r=PXWZR3CDCTCERY910D7C&pd_rd_r=86b502c4-8797-4d8c-a28e-163845214cbf

An phone app called "Noonlight", which can alert authorities and share your location by just tapping a button.

https://www.noonlight.com/noonlight-app

Phone case taser

https://yellowjacketcase.com/

Personal alarm

https://www.amazon.com/KOSIN-Personal-Security-Keychain-Emergency/dp/B07NLFQS7T/ref=sr_1_7_sspa?keywords=personal+alarm&qid=1637946162&s=electronics&sr=1-7-spons&psc=1&smid=AS13C0CXK53V9&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzQjU5REQ2ODA2VjJEJmVuY3J5cHRlZElkPUEwMzg2Nzg5Mkw4Q05KWFJBVEJZViZlbmNyeXB0ZWRBZElkPUEwMTk3MzEwMUoxNTdRM1RXOFJTVCZ3aWRnZXROYW1lPXNwX210ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

Added from comments:

Hairspray and lighter

Rape whistle

Tactical pen

Baton

Firearms, if legally owned and w/ knowledge of gun safety

-specifically, Glock 43x 9mm, with concealed carry license if needed

I'm also curious to see what tools you all use, I would love to add them to this list!

Edit: There are certain situations that cannot be avoided. If my car is not working and I am taking an Uber in the middle of the day with a five star reviewed driver he could still be a rapist or a creep. I would rather be in possession of a car window breaker than nothing. Yes self defense classes are vital but to discourage women from investing in tools that could benefit them is dangerous.