Size Matters Vol. 1: Keychain (0"–2")
The smallest category, the hardest brief. A blade under two inches has to earn every millimeter, because at this scale, a knife that's merely good is a knife you don't bother carrying.
The keychain knife is the hardest thing to get right in this hobby. You're trying to make something small enough to live on a keychain or in a coin pocket indefinitely, functional enough to be worth the real estate, sharp enough to do actual cutting work, and interesting enough that you chose it over just not carrying one at all. Most attempts fail at least one of these. The ones that succeed are worth talking about.
This category covers blades up to two inches. That's a strict ceiling, and it forces honesty, a knife at this size is not replacing your daily carry, it's supplementing it, or it's the backup you forget about until you need it. The best ones earn their keep every time.
Series context: This is Vol. 1 of our four-part Size Matters series, which breaks the folder world into honest carry categories rather than arbitrary inch increments. The other volumes cover 5th pocket (2"–2.8"), standard (2.9"–3.5"), and big boys (3.5"+).
A 0.42" blade in M390 is not a sentence you expect to write. But here we are. Caleb Waldman designed a coin-knife-sized slipjoint around a steel that normally shows up in folders costing four times as much, because a hawkbill blade at this scale gets used primarily for precision cutting tasks where edge retention actually matters. The detent mechanism holds the blade in position without a true lock, the 360° rotation means no wrong orientation, and the machined aluminum body disappears into a coin pocket or onto a keyring without complaint. The AEB-L version at $49.97 is the practical choice. The M390 version at $89.97 with Timascus accents is for people who want to do this right.
The Microblade is the knife that launched WESN as a brand, which tells you something about the clarity of the concept. Billy Chester wanted a blade tiny enough to live on your keychain, made of materials good enough to not embarrass you, and the Microblade is exactly that. D2 in a 1.5" blade with titanium handles, at a size most manufacturers would have used pot metal, WESN used titanium. It shows in how it carries and how it lasts. The drop point is useful rather than aggressive. The split ring integrates cleanly. This is the keychain knife that made the category feel legitimate.
The Elementum is a hall-of-fame EDC folder, and CIVIVI didn't dilute the concept by scaling it down, they just made it smaller and added a keyring. The 1.83" blade in 14C28N is sharp from the factory, the hand-rubbed brass or copper finish gives it character that most production knives at this price lack entirely, and the frame lock works cleanly at scale. At $42 it's the most affordable serious entry in this category. If you've never carried a keychain knife and want to understand what the appeal is without spending $75, start here.
The Ladybug has been around for decades and is still the standard reference point for the category. VG-10 with a compression lock at 0.6 oz, almost nothing to it, and that's the point. The FRN handles keep weight essentially negligible. The Spydie hole opener works at this scale with some practice. The compression lock is safe and reliable. At just under two inches it sits at the top of this category by blade length, and it uses that length efficiently. If you know you want a keychain knife and prefer a proven design over something newer, the Ladybug remains the correct answer.
Four knives, that's the whole category. Not because there aren't others, but because the brief is specific enough that most options fail it. A blade under two inches that's worth carrying on your keys or in your coin pocket needs to be genuinely small, made of materials that won't embarrass you, and functional enough that you reach for it. These four do that. The Snail-Trail in M390 is the most ambitious. The Ladybug is the most proven. Pick based on what you want the experience to be.