On what you get without paying, 21st.dev does not publish it and shadcn/ui registry directory is All of it. On cheapest paid option, 21st.dev is $6/month, billed yearly (Builder) and shadcn/ui registry directory does not publish it. On what it publishes, 21st.dev is 12,000+ components, templates and themes and shadcn/ui registry directory does not publish it. On how you install from it, 21st.dev is Copy a prompt, or MCP and CLI and shadcn/ui registry directory is npx shadcn add @<registry>/<component>. On how something gets listed, 21st.dev does not publish it and shadcn/ui registry directory is A documented add-a-registry route. On what it says about the code's quality, 21st.dev is Authorship, stated as the guarantee and shadcn/ui registry directory is Explicitly not reviewed, and it says so. BlockDex publishes this table and is one of the things in it, so read the case for the other side below rather than taking the table's word for it. Every figure was read off the named company's own page on or since 2026-09-06; the URLs and the dates are at the foot of this page, and a job re-fetches each one on a schedule and fails when a figure is no longer on the page it came from.

BlockDex publishes this table and is not one of the 2 compared. "Not published" means that company does not state the figure on the page cited below. It is not a claim that no such figure exists: this table prints what was read, not what was inferred.

When each of these is the right pick

BlockDex does not sell any of these and scores them. Each case below is the one that option wins.

• 21st.dev: You want breadth and you work by pasting a prompt into an agent rather than by running a CLI. It is the largest catalogue of the four at "12,000+ crafted React components, templates, and shadcn themes", it is the only one whose delivery mechanism is the prompt itself — "every component ships as a prompt. One copy - and it builds itself in whatever tool you live in" — and it is the cheapest recurring entry here at $6 a month billed yearly, with unlimited MCP and CLI retrieval on that tier.
• shadcn/ui registry directory: You want the first-party answer and the shortest possible path from finding a component to having it in your repository. This is the mechanism every other entry here sits on top of, it costs nothing, and the registries in it are "built into the CLI with no additional configuration required" — so `npx shadcn add @<registry>/<component>` works with no account, no key and no config. It is also the only one of the four that tells you plainly what it does not do.

Other shadcn registries and block libraries compared head to head

• 21st.dev vs awesome-shadcn/ui
• 21st.dev vs Shoogle
• shadcn/ui registry directory vs awesome-shadcn/ui
• shadcn/ui registry directory vs Shoogle
• shadcnblocks.com vs shadcn/ui registry directory

What was checked, and when

Prices and limits move. Every source is printed here so a reader can check it on the day they read this, and a job re-fetches each of these URLs on a schedule and fails when a figure above no longer appears on the page it came from.

• 21st.dev, 21st.dev/pricing: What you get without paying, Cheapest paid option, How you install from it, How something gets listed. Read 2026-09-06.
• 21st.dev, 21st.dev/: What it publishes, What it says about the code's quality. Read 2026-09-06.
• shadcn/ui registry directory, ui.shadcn.com/directory: What you get without paying, Cheapest paid option, What it publishes, How you install from it, How something gets listed, What it says about the code's quality. Read 2026-09-06.

Every cell above was confirmed against its own source on or since 2026-09-06. /compare/21st-dev-vs-shadcn-registry