diff --git a/source/UnixTime.popclipext/test.js b/source/UnixTime.popclipext/test.js
index 06400a2b..8340c7ca 100644
--- a/source/UnixTime.popclipext/test.js
+++ b/source/UnixTime.popclipext/test.js
@@ -7,6 +7,7 @@ const testData = new Map([
 	[["1535438729", 'Europe/London', 'gb'] , "28/08/2018, 07:45:29 BST"],
 	[["1535438729", 'America/New_York', 'zu'] , "2018-08-28 02:45:29 GMT-4"],
 	[["1535438729", 'Pacific/Honolulu', 'zu'] , "2018-08-27 20:45:29 GMT-10"],
+	[["1762265252513", 'UTC', 'zu'] , "2025-11-04 14:07:32 UTC"],
 ]);
 
 let fail = false;
diff --git a/source/UnixTime.popclipext/unixtime.js b/source/UnixTime.popclipext/unixtime.js
index 3d90a253..5b1ce283 100644
--- a/source/UnixTime.popclipext/unixtime.js
+++ b/source/UnixTime.popclipext/unixtime.js
@@ -10,9 +10,62 @@ const defaultLocale = ["zu", "International Standard"];
 // Used to unset params if it's chosen, allowing environment defaults to be used.
 const systemSetting = ["", "System"];
 
+// Detect if input is a date string or Unix timestamp
+const isDateString = (input) => {
+	const cleaned = input.trim();
+	// Negative numbers are always timestamps (Unix epoch can be before 1970)
+	if (cleaned.startsWith('-') && /^-[\d\s]+$/.test(cleaned)) {
+		return false;
+	}
+	// If it contains date separators or is clearly a date format
+	if (/[-\/]/.test(cleaned) || /^\+\d+-\d+-\d+/.test(cleaned) || /^\d{4}-\d+-\d+/.test(cleaned)) {
+		return true;
+	}
+	// If it's all digits (possibly with spaces), treat as Unix timestamp
+	return !/^[\d\s+-]+$/.test(cleaned);
+}
+
+// Parse date string to Date object
+const parseDateString = (dateString) => {
+	// Remove UTC timezone indicator if present
+	let cleaned = dateString.trim().replace(/\s*UTC\s*$/i, '');
+	
+	// Handle extended year format with + sign (e.g., +057813-12-18 13:41:53)
+	if (cleaned.startsWith('+')) {
+		// Remove the + sign for parsing
+		cleaned = cleaned.substring(1);
+	}
+	
+	// Try to parse the date string
+	const date = new Date(cleaned);
+	
+	// Validate the date
+	if (isNaN(date.getTime())) {
+		throw new Error(`Invalid date string: ${dateString}`);
+	}
+	
+	return date;
+}
+
 const process = (selection, options) => {
-	const unixTime = selection.replace(/\s/g, ''); // remove spaces;
-	const date = convert(unixTime);
+	const trimmed = selection.trim();
+	
+	let date;
+	
+	// Detect if input is a date string or Unix timestamp
+	if (isDateString(trimmed)) {
+		// Parse as date string
+		date = parseDateString(trimmed);
+	} else {
+		// Parse as Unix timestamp
+		const unixTime = trimmed.replace(/\s/g, ''); // remove spaces
+		date = convert(unixTime);
+	}
+
+	// Validate date
+	if (isNaN(date.getTime())) {
+		throw new Error(`Invalid input: ${trimmed}`);
+	}
 
 	const custom_settings = (options.timeZone !== defaultTimezone[0] || options.locale !== defaultLocale[0])
 	if (custom_settings) {
@@ -27,9 +80,115 @@ const process = (selection, options) => {
 }
 
 const convert = (unixTime) => {
-	const seconds = unixTime;
-	const milliseconds = 1000;
-	return new Date(seconds * milliseconds)
+	// Remove any non-numeric characters except +, -, and spaces
+	const cleaned = unixTime.replace(/[^\d\s+-]/g, '').replace(/\s/g, '');
+	const timestamp = parseFloat(cleaned);
+	
+	if (isNaN(timestamp)) {
+		throw new Error(`Invalid Unix timestamp: ${unixTime}`);
+	}
+	
+	// Unix timestamp standard: seconds since 1970-01-01 (Unix epoch)
+	// Optimal detection algorithm combining digit count and date range validation
+	// Based on industry standards (epochconverter.com, unixtimestamp.com) and
+	// avoiding pitfalls from naive approaches (see Pydantic issue #7940)
+	
+	// Handle negative timestamps (before 1970) - always treat as seconds
+	// Negative timestamps are rarely used in milliseconds in practice
+	if (timestamp < 0) {
+		return new Date(timestamp * 1000);
+	}
+	
+	// Calculate digit count (handle edge case for 0)
+	const digitCount = timestamp === 0 ? 1 : Math.floor(Math.log10(Math.abs(timestamp))) + 1;
+	
+	// Try both interpretations for ambiguous cases (11-12 digits: seconds vs milliseconds)
+	if (digitCount === 11 || digitCount === 12) {
+		const dateAsSeconds = new Date(timestamp * 1000);
+		const dateAsMilliseconds = new Date(timestamp);
+		
+		// Validate date ranges: reasonable Unix epoch dates (1970-2300)
+		// This prevents false positives for old timestamps in milliseconds
+		// Extended to 2300 to handle edge cases like 2286 (max reasonable 10-digit seconds)
+		const yearAsSeconds = dateAsSeconds.getFullYear();
+		const yearAsMilliseconds = dateAsMilliseconds.getFullYear();
+		
+		const isValidYear = (year) => year >= 1970 && year <= 2300;
+		
+		const secondsValid = isValidYear(yearAsSeconds);
+		const millisecondsValid = isValidYear(yearAsMilliseconds);
+		
+		if (millisecondsValid && !secondsValid) {
+			// Only milliseconds gives valid date
+			return dateAsMilliseconds;
+		} else if (secondsValid && !millisecondsValid) {
+			// Only seconds gives valid date
+			return dateAsSeconds;
+		} else if (millisecondsValid && secondsValid) {
+			// Both valid - use magnitude heuristic:
+			// Threshold: 1e10 (10 billion) - if timestamp is larger, prefer milliseconds
+			// This handles cases like 10000000000 (10 billion) where both are valid
+			// but milliseconds interpretation is more likely for 11-12 digit numbers > 10 billion
+			if (timestamp >= 1e10) {
+				return dateAsMilliseconds;
+			} else {
+				// Prefer seconds (Unix standard) for smaller values
+				return dateAsSeconds;
+			}
+		}
+		// Neither valid - fall through to digit count logic
+		// If neither gives valid date, prefer milliseconds for 11-12 digits
+		// (as they're more likely to be JavaScript timestamps)
+		if (digitCount === 11 || digitCount === 12) {
+			return dateAsMilliseconds;
+		}
+	}
+	
+	// Try both interpretations for ambiguous cases (14-15 digits: milliseconds vs microseconds)
+	if (digitCount === 14 || digitCount === 15) {
+		const dateAsMilliseconds = new Date(timestamp);
+		const dateAsMicroseconds = new Date(timestamp / 1000);
+		
+		// Validate date ranges: reasonable Unix epoch dates (1970-2300)
+		// Extended to 2300 to handle edge cases like 2286 (max reasonable 10-digit seconds)
+		const yearAsMilliseconds = dateAsMilliseconds.getFullYear();
+		const yearAsMicroseconds = dateAsMicroseconds.getFullYear();
+		
+		const isValidYear = (year) => year >= 1970 && year <= 2300;
+		
+		const millisecondsValid = isValidYear(yearAsMilliseconds);
+		const microsecondsValid = isValidYear(yearAsMicroseconds);
+		
+		if (millisecondsValid && !microsecondsValid) {
+			// Only milliseconds gives valid date
+			return dateAsMilliseconds;
+		} else if (microsecondsValid && !millisecondsValid) {
+			// Only microseconds gives valid date
+			return dateAsMicroseconds;
+		} else if (millisecondsValid && microsecondsValid) {
+			// Both valid - prefer milliseconds (more common in practice)
+			return dateAsMilliseconds;
+		}
+		// Neither valid - prefer milliseconds for 14-15 digits
+		if (digitCount === 14 || digitCount === 15) {
+			return dateAsMilliseconds;
+		}
+	}
+	
+	// Clear cases based on digit count (industry standard)
+	if (digitCount <= 10) {
+		// Standard Unix timestamp in seconds
+		return new Date(timestamp * 1000);
+	} else if (digitCount === 13) {
+		// Milliseconds (JavaScript Date format) - clear case
+		return new Date(timestamp);
+	} else if (digitCount === 16) {
+		// Microseconds - convert to milliseconds - clear case
+		return new Date(timestamp / 1000);
+	} else if (digitCount > 16) {
+		// Nanoseconds - convert to milliseconds
+		return new Date(timestamp / 1000000);
+	}
 }
 
 const standardize = (date, clean = false) => {
@@ -58,7 +217,13 @@ const buildFormat = (locales = [], custom_options = {}) => {
 
 module.exports = {
 	action(selection, context, options) {
-		popclip.showText(process(selection.text, options))
+		try {
+			const result = process(selection.text, options);
+			popclip.copyText(result);
+			popclip.showText(result);
+		} catch (error) {
+			popclip.showText(`Error: ${error.message}`);
+		}
 	},
 	icon: "UnixTime.png",
 	options: [