What is a font tester?

A font tester is a tool that lets you preview how a typeface looks before you use it in a design or website. Instead of installing a font on your operating system or embedding it in a project, you can load it directly in the browser and see exactly how letters, numbers, and symbols are rendered. This is especially useful for evaluating custom or unfamiliar fonts, since the visual character of a typeface — its proportions, weight, spacing, and rhythm — can only be judged in context with real text.

Modern browsers expose the FontFace API, which makes it possible to register a font from a local file and apply it to any element on the page without uploading anything to a server. All rendering happens locally, so the font file never leaves your device.

Tool description

This Font Tester lets you upload a font file (TTF, OTF, WOFF, or WOFF2) and instantly preview it with fully customizable typography settings. You can adjust size, line height, letter spacing, word spacing, weight, style, alignment, and colors, then see the result rendered live across multiple specimens — sample text, full alphabet, digits, symbols, and a size scale — to evaluate the typeface from every angle.

The font is loaded entirely in the browser; no upload, account, or installation is required.

Examples

Input: A custom .woff2 file plus the sample text The quick brown fox jumps over the lazy dog.

Output: A live preview of that sentence rendered in the uploaded font at the chosen size, weight, and spacing, plus separate panels showing the uppercase alphabet, lowercase alphabet, digits, symbols, and the same pangram repeated at 12, 16, 20, 24, 32, 48, 64, and 96 pixels.

Features

  • Local font loading: Drop in a TTF, OTF, WOFF, or WOFF2 file and see it applied immediately
  • Full typography controls: Adjust font size, line height, letter spacing, word spacing, weight, italic, and alignment
  • Color customization: Pick text and background colors to test contrast and on-brand combinations
  • Multiple specimens: Preview the font with custom text, the full alphabet, digits, symbols, and a size scale
  • Privacy-friendly: Files are processed in your browser and never uploaded to a server

Use cases

  • Evaluating a purchased or downloaded font: Try a typeface across sizes, weights, and colors before committing it to a brand or project
  • Testing webfont rendering: Check how a .woff2 file actually displays in the browser, including kerning, spacing, and italic style
  • Designing typography for a website or app: Iterate quickly on font size, line height, and letter spacing to find the right combination

Supported formats

  • TTF (TrueType Font)
  • OTF (OpenType Font)
  • WOFF (Web Open Font Format)
  • WOFF2 (Web Open Font Format 2.0)

Options explained

  • Sample text — The text shown in the main preview panel; supports multiple lines.
  • Font size — Size of the main preview text in pixels (8–200). The alphabet, digit, and symbol panels render at 75% of this value.
  • Line height — Vertical spacing between lines, expressed as a percentage of the font size (50–300%).
  • Letter spacing — Extra space between individual characters, in pixels (-10 to 30). Negative values tighten the text.
  • Word spacing — Extra space between words, in pixels (-10 to 50).
  • Font weight — Numeric weight from 100 (Thin) to 900 (Black). Only weights actually included in the font file will render distinctly; others are simulated by the browser.
  • Italic — Toggles font-style: italic. If the font has no italic variant, the browser may synthesize a slanted version.
  • Text align — Left, center, right, or justify alignment for the preview panels.
  • Text color / Background color — Colors used in every preview panel, useful for previewing the font on its intended background.

Tips

  • Some fonts only ship a single weight; switching to bold or thin may look identical or fall back to a synthetic browser style. Check the font's documentation if a weight looks wrong.
  • Use the size scale panel to spot fonts that hint poorly at small sizes — a typeface that looks elegant at 64px can become unreadable at 12px.
  • Test your font against both light and dark backgrounds; thin weights often disappear on dark backgrounds and need to be bumped up.
  • Compare uppercase and lowercase panels side by side to evaluate x-height, cap height, and overall rhythm.

Limitations

  • Variable font axes beyond standard weight and italic are not exposed individually.
  • OpenType features such as ligatures, stylistic alternates, and small caps are rendered using the browser's defaults and cannot be toggled in the UI.
  • Very large font files may take a moment to load and parse.