A clipboard viewer online cheat sheet begins with the seven measurements the tool reports on any pasted or read text: character code units, Unicode code points, UTF-8 byte length, logical lines, word-like tokens, whitespace characters, and a strict JSON parse result. Clipboard Viewer performs every one of those inspections locally in your browser tab, so the values appear immediately as you type or paste. The counts are independent and serve different debugging purposes, which is why a string can look correct yet still trip a parser, a YAML loader, or a database column constraint. Knowing which number answers which question is the core of this cheat sheet, along with the invisible-character overlay that makes spaces, tabs, and line endings visible without modifying the underlying value. The tool reads text only — never images, rich HTML, files, or platform-specific clipboard formats — and analysis stays in the current tab, so no pasted clipboard contents are submitted to a remote server.
What the Seven Counts Measure
Each counter answers a distinct question, and the answers can disagree for the same input. JavaScript character length counts UTF-16 code units, the code-point count treats every Unicode code point as one item, and the UTF-8 byte length reflects what most files, network protocols, and storage layers actually consume. Lines recognize LF, CRLF, and standalone CR as separators, while words use Unicode letters and numbers with internal apostrophes, underscores, and hyphens as token boundaries. The whitespace counter counts every space, tab, and line-ending character, and the JSON indicator reports whether the trimmed text passes a strict JSON.parse check. The split between these numbers is not a flaw. JavaScript strings are sequences of UTF-16 code units by default, so supplementary characters expand to two code units and inflate the character counter without changing the code-point total. UTF-8 is variable-width and often the most relevant measure for network and storage budgets, since ASCII characters take one byte, common Latin characters take two, BMP characters between U+0800 and U+FFFF take three, and characters outside the Basic Multilingual Plane take four.
| Count | What it measures | Typical debugging use |
|---|---|---|
| Character code units | JavaScript .length in UTF-16 code units | String truncation, slice, and substring math |
| Unicode code points | Each code point as one item via Array.from | Emoji, supplementary plane, and BMP boundary checks |
| UTF-8 bytes | TextEncoder byte length | Storage quotas, API body limits, and network framing |
| Logical lines | Split on LF, CRLF, and standalone CR | File format diagnostics and CSV row counts |
| Word-like tokens | Unicode letters and digits with ', _, - inside | Quick content sanity checks |
| Whitespace characters | Every space, tab, carriage return, and line feed | Detecting hidden indentation or trailing whitespace |
| JSON validity | Strict JSON.parse on the trimmed text | Verifying payload syntax before sending |
Read these counts side by side rather than in isolation. A string that reports 11 characters but 9 code points is not corrupted; it contains supplementary characters that occupy two UTF-16 code units each. A payload that shows 220 UTF-8 bytes but only 180 characters is signalling multi-byte characters, not double counting. This cheat sheet's job is to make those gaps visible so you can pick the right counter for the constraint you are debugging.
How to Inspect Clipboard Text with the Online Viewer
- Open the Clipboard Viewer in a focused browser tab over HTTPS, then click Read clipboard and approve the browser permission prompt. If the browser denies the request, or you prefer not to grant access, paste the text directly into the editor with the standard paste shortcut.
- Compare the seven reported results side by side: character code units, Unicode code points, UTF-8 bytes, logical lines, words, whitespace characters, and the JSON indicator. Treat each value as an independent answer to a specific question about the text.
- Enable the Show spaces, tabs, and line endings overlay whenever the formatting might be the problem — for example, when comparing copied shell commands, YAML indentation, CSV rows, or text moved between Windows, macOS, and Linux. The overlay is display-only; the underlying editor value is unchanged.
- Read off the result, copy what you need, then click the editor's clear control to remove the working value from component state. Do this before moving on when the clipboard contained tokens, credentials, personal data, or customer information.
Reading the Invisible-Character Overlay
The overlay substitutes every invisible character with a visible glyph while leaving the stored value untouched. Spaces become centered dots, tabs become arrows, and line endings render as explicit symbols so you can tell at a glance whether the text uses LF, CRLF, or CR separators. This is the fastest way to catch the four classic clipboard bugs: a trailing space at the end of a password, a stray tab inside a CSV cell, mixed line endings in a script edited on both Windows and Linux, and a hidden carriage return that survives a copy from a terminal. For deeper debugging of hidden formatting, the step-by-step approach in How to View the Clipboard and Inspect Hidden Text Details pairs well with this overlay and shows how to confirm the suspected culprit with a second pass through the editor.
JSON Validity Check and What It Does Not Do
The JSON indicator performs a strict JSON.parse against the trimmed text and reports only whether the syntax is valid. It does not repair JSON, run any code, follow links, or interpret pasted HTML. A green result means the trimmed payload is syntactically valid JSON, not that its fields are safe, complete, semantically correct, or free of malicious values. Use it as a fast preflight before sending a payload to an API or storing it in a JSON column, and reach for a dedicated validator when you need error positions, schema checks, or schema-driven validation.
Browser Permissions and Privacy Boundaries
Direct clipboard reads are a protected browser capability. According to MDN's Clipboard.readText reference, the call usually requires a secure context, a focused page, a user gesture, and an explicit permission grant. The W3C Clipboard API and events specification describes the same gating model across browsers. Even when those conditions are met, the request can be denied because of user settings, enterprise policy, embedded-page restrictions, or an unsupported API surface.
A denial is not treated as lost data: the tool surfaces a clear message and the normal paste shortcut remains available. Manual paste is also the right choice whenever you want to control exactly which characters enter the page. The HTTPS requirement also explains why the same tool can fail when loaded from a local file path or behind an untrusted certificate, and the user-gesture requirement means the read has to follow a click or key press, so scripted polling of the clipboard is not supported and is not attempted. None of those restrictions apply to the editor: typing and pasting update the counts immediately, which is why manual paste is the recommended route for sensitive material. Privacy is the main design constraint overall: analysis happens in the current tab, the clipboard text never leaves the browser, and clearing the editor removes the working value from component state.
Common Clipboard Bugs the Cheat Sheet Exposes
Each pattern below maps a misbehavior to a specific counter or overlay signal. Use them as a triage list when you have a copied value and a vague description of the symptom, then read the actual counts on the Clipboard Viewer page to confirm.
- Trailing space in a token. The whitespace counter is non-zero while the character counter is one more than you expected. The overlay pins the space to the end of the line.
- Mixed line endings after a cross-platform copy. The logical-line count matches a Unix reader but a Windows tool reports extra rows. The overlay shows the CRLF markers concentrated near the seams between edited regions.
- Hidden carriage return inside a value. Word count looks right, but the character counter is higher than expected and the overlay shows a CR glyph mid-line.
- Emoji that break a string-length assumption. Character code units report one more than code points for each supplementary character, while UTF-8 bytes jump by four per code point.
- JSON that almost parses. The JSON indicator shows invalid even though the payload looks balanced, which usually points to a stray comma, an unescaped quote, or a non-breaking space in a key — and the overlay makes that last case obvious.
Related reading: CSS Loader Generator Cheat Sheet: Inputs, Bounds, Output.