Hashtag Counter & Extractor (Per-Platform Caps, 2026)

A hashtag is a # followed by letters, numbers, or underscores — and it ends at the first character that isn’t one of those. That single rule explains most “why didn’t my tag work” mysteries: #spring-sale links only as #spring, #50%off dies at the percent sign, and a space anywhere splits the tag in two. Emoji and punctuation don’t just fail silently; they cut the tag short at exactly that point. The extractor above applies the same rule the platforms do, so what it finds is what will actually link.

Capitalization, by contrast, never splits a tag: #SummerSale and #summersale are the same hashtag everywhere. That’s why the list above lowercases and merges them — and flags the merge as a duplicate, because posting both spends characters twice for zero extra reach.

The reason a per-platform check matters in 2026: Instagram ended the tag-block era by rolling out a 5-hashtag cap (counted across caption and comments) starting December 2025, and Threads launched with a single topic tag per post — two networks where “how many” is now a hard rule, not a style choice. Pinterest sits in between, accepting up to 20 but de-emphasizing them, and YouTube shows only the first 3 above the title while ignoring every tag on videos that stack an excessive number.

Everywhere else, the cap is really a character budget. On X, each tag eats into 280 characters; on Bluesky, into 300 graphemes. The total-characters-consumed figure above tells you what your tag habit costs — check the matching character counter to see what’s left for the actual message.

The duplicate flag earns its keep on recycled captions: paste last month’s post and you’ll often find the same tag living in the caption and the copied comment block. Dedupe first, then prune to tags that describe what is actually in the post — on every network, a handful of specific tags has outlasted the wall-of-30 approach, and on Mastodon specific tags are the discovery mechanism. The Copy-cleaned-tags button hands back the deduplicated, lowercased set ready to paste.

If you cross-post, run the same caption against each platform before scheduling: a tag set that passes Pinterest fails Instagram, and the one tag Threads allows should be your best one. SocialKit’s composer does this continuously — it shows each network’s limits while you write one post for all 11 platforms, so the per-platform tag trim happens before publish, not after the error message.