My kit:

• pocket knife
• flashlight
• wallet
• folding phone stand
• phone
• earbuds
• pen (with a cap, not a clicky)
• sharpie
• breath mints
• 4' multi-end charging cable
• thumb drive
• lightning > 3.5mm (aux)
• USBC > 3.5mm
• bandaids
• OTC drugs (Advil, Tylenol, Aleve, Benadryl, lactase (I'm lactose intolerant))

Everything on that list was added because I needed it and didn't have it on multiple occasions. There have been plenty of other things that I would love to carry, but found too bulky to justify.

A note to everyone recommending condoms: they do expire, and can wear through if carried in an environment with friction (wallet, pocket, etc). I prefer to play it safe and make a stop at a drug store should the need arise.

I always carry a pepper spray with me just in case!

Hand sanitizer.

A carry this kind of multitool with my keys

And this ceramic blade box cutter

Leatherman Skeletool and a bullet space pen pretty much cover all my day to day needs. I used to carry a bootable flash drive with all the software tools I used frequently but haven't needed that on the go since I changed jobs so it lives in my desk at home now.

A lockpick set. You never know.

A tracker on my key for when i lose it.

A knife. I use mine about once a week.

I’ve found a Gerber Dime to be really handy when I can’t carry my Leatherman. I usually carry a lockblade knife, multitool, and Fischer space pen. Also have a USB drive on my keychain partitioned with NTFS (bulk storage) and Tails with persistence.

A bottle opener. You never know when a wild beer might appear

I've carried a Swiss Tech Utili-Key on my keychain for 20+ years now. It's got a knife, a flathead screwdriver, a Phillips screwdriver, an eyeglass screwdriver, and a bottle opener. It's the same size and shape a regular key and security never notices it.

A good flashlight.

Mostly indoors? Small, 300lm light that takes a AAA battery like the Maker E02II.

Mostly outdoors? Medium sized light that uses an 18650, like the (now discontinued) Zebra Light H600w Mk IV.

Mobile gaming? Battery bank flashlight like the Wurkkos HD20!

Right angle flashlights are easier to hold, use in a headlamp strap, and often have magnetic tail caps to mount to a metal surface.

• They make belt buckles that double as bottle openers for roadside Topo Chico and tacos, or beer (not roadside, don't drink and drive).
• I have a tough little metal USB drive with a size A jack on one side, whatever fits my phone on the other, and firmware to be able to plug into said phone.
• Musicians ear plugs in a tough metal keyring pill case.

I always carry a small Victorinox Navaja classic swiss army knife linked to a small Fenix torch E01. It fits inside the lighter pocket of my jeans.

Also always carry a handkerchief (fabric, not disposable).

As mentionned already, I usually also have earplugs in my jacket or bag. A Go-Girl is a must have too when traveling if you don't have a pee-pee.

https://www.streamlight.com/products/detail/nano-light#

I have had one for a lot of years, I use it a lot.

Cellphone and key to your car/house. Eftpos card, bus card and $20 and library card.

SIM tools :)