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Components / Component registry

21st

Find concrete React examples and prompts for a UI draft.

Documentation reviewed

Source review

What this status means

Understand the resource

What it is.

21st presents a library of React components, templates and shadcn themes with agent-oriented prompts. It is a discovery layer whose individual contributions still need code, dependency and rights review.

When it is useful

You want to compare ready-made approaches to a particular section.

A proposed application

Put it to work.

This example illustrates a possible use. The proposed workflow and expected result are separate from the bounded checks recorded below.

Try this

Select one pricing comparison block, inspect its source and replace all sample offers before testing the narrow layout.

Result to aim for

A reviewable component draft tailored to actual requirements.

Before you start

What you need.

  • A compatible React project and a review process for third-party code or prompts.

The practical boundaries

What to watch for.

  • Registry or MCP access is a software supply path; inspect what an agent will install or modify.
  • Community authors, dependency requirements and reuse terms can differ between entries.

Review record

What we could establish.

  • Public primary documentation and the bounded account-free checks below were reviewed. A public Hover Button detail exposed one preview frame and one code block. The sample was reachable without an account; the component was not installed or functionally exercised inside that frame.
Source coverage and runtime coverage are separate

The source-review notes describe documentation and identity. The account-free evaluation below records exactly which public interaction or local fixture was checked, what happened, and what remains untested.

Check current access, terms, licensing and data handling before using a resource with your own material.

Runtime and security evaluation

What the evaluation covers.

Limited evaluationAccount-free ·

A public Hover Button detail exposed one preview frame and one code block. The sample was reachable without an account; the component was not installed or functionally exercised inside that frame.

Methods: Public HTTP response · Public browser sample. A completed check covers the stated sample; it is not a safety certification.

Target
https://21st.dev/@serafimcloud/components/hover-button
Version or capture
Unversioned public page checked 2026-10-19
Integrity scope
sha256:9bd7ba4c482e8b7e9cc93613da50b8f1dc4c10e60f8a20bf7bd54c8bfa8f53b5

Test conditions

  • Chromium 155.0.8059.82 on Windows; fresh temporary profile and fresh account-free contexts.
  • Public HTTPS GET/HEAD requests only; telemetry/auth routes and WebSockets blocked. No account storage or credential environment variables.

Individual checks and observations

  1. Public document and DOM

    pass

    Public browser sample: Fresh Chromium GET, then inspect rendered controls after hydration delay

    Observed: HTTP 200; 27 captured button labels; 0 inputs; 1 canvases.

  2. Public component detail

    pass

    Public browser sample: Load the linked Hover Button detail and inspect preview availability

    Observed: Detail rendered 1 child frames and 1 code blocks; preview label false. No component installed or bookmark saved.

Security findings and boundaries

Passive inspection of the public response headers, requested hosts and the named browser sample. No active exploitation, authenticated permissions test or complete security audit.

Observed · caution

Community preview code needs its own review

A preview frame was present on the public detail. Its availability does not validate the component source, dependencies or execution permissions in your project.

Practical caveats

  • Review the individual author, license, imports and external requests before importing a community component.
  • Pin and recheck the selected version or sample before adoption; the observations apply only to the scope and date shown.

What remains untested

  • No iframe isolation audit, component installation, paid content or authenticated registry workflow.
  • Fresh-browser restrictions can affect external assets and hydration. Initial failed selectors and limited probes remain in the evidence; they are not blanket product failures.

Security limits

  • No authenticated workspace, private content, production backend permissions or data-retention verification.
  • No iframe isolation audit, component installation, paid content or authenticated registry workflow.

Evaluation sources

  1. Primary public resource
  2. Evaluated public sample

Download this evaluation record (JSON)

Follow the evidence

Sources and further reading.

  1. Primary product documentation

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