WCAG カラー コントラスト チェッカー — AA および AAA 準拠のテスト

Poor color contrast excludes visually impaired users and exposes your site to accessibility lawsuits. Test any two colors against WCAG 2.1 standards instantly.

WCAG コントラスト コンプライアンスとは何ですか?

The Web Content Accessibility Guidelines (WCAG) define minimum contrast ratios between text and background. Normal text needs 4.5:1 for AA and 7:1 for AAA. Large text needs 3:1 for AA and 4.5:1 for AAA. These ratios are calculated from the relative luminance of each color.

なぜコントラストが重要なのでしょうか?

Low contrast text is hard or impossible to read for people with low vision, color blindness, or anyone using a screen in bright sunlight. It is also a common reason for ADA lawsuits in the US and EN 301 549 non-compliance in Europe.

このツールはどのように機能するのでしょうか?

Pick a text color and a background color. The tool calculates the contrast ratio and shows you at a glance whether you pass or fail AA and AAA for both normal and large text. Everything runs locally — no color data is sent anywhere.

ブラウザベースのユーティリティ ツールを使用する理由は何ですか?

Online utilities like password generators, text formatters, and URL cleaners are convenient, but most send your data to remote servers. Our browser-based tools process everything locally — your passwords, text, and URLs never leave your device.

This is especially important for sensitive operations like generating passwords, checking password strength, or cleaning URLs that contain tracking parameters. With Presend, you get the convenience of online tools with the security of offline software.

当社のユーティリティツールがあなたのプライバシーをどのように保護するか

1. All processing happens in your browser using JavaScript
2. No data is transmitted to external servers
3. No cookies or tracking scripts monitor your usage
4. Your input data is cleared when you close the tab

当社のユーティリティ ツールを使用すると何ができるでしょうか?

Generate cryptographically secure passwords, check password strength against entropy analysis, convert between JSON and CSV formats, compare text differences, split long text into social media threads, clean tracking parameters from URLs, validate email lists, check color contrast for accessibility, and convert images to Base64 for embedding.

これらのツールは本当に無料ですか?

Yes — all our utility tools are completely free to use, with no registration required, no usage limits, and no watermarks. We believe privacy tools should be accessible to everyone, not locked behind paywalls or subscription models.