Bidi Text Analyzer
Analyze text for hidden Unicode bidirectional control characters. Detect Trojan Source attacks, unmatched pairs, and security risks.
Bidi Text Analyzer
Detect hidden bidi characters
What This Tool Detects
- Direction Marks: LRM, RLM, ALM - zero-width directional hints
- Embeddings: LRE, RLE - embed directional text runs
- Overrides: LRO, RLO - force display direction
- Isolates: LRI, RLI, FSI - modern directional isolation
- Pop Characters: PDF, PDI - close embeddings/isolates
- Trojan Source: Detects CVE-2021-42574 attack patterns
How to Use
- Paste text that may contain hidden bidirectional control characters
- Click "Analyze Bidi Characters" to scan the text
- Review the security risk assessment and character breakdown
- View the visualized text to see where bidi chars are located
- Copy the cleaned text with all bidi characters removed
Frequently Asked Questions
What is a Trojan Source attack?
Trojan Source (CVE-2021-42574) is a vulnerability where bidirectional override characters are used to make source code appear differently than it actually executes. Attackers can use RLO/LRI characters to visually reorder code, hiding malicious logic in plain sight.
Why should I analyze text for bidi characters?
Hidden bidi characters can cause text to display differently than expected, create security vulnerabilities in source code, cause issues with text processing, and lead to confusing behavior in multilingual documents. This tool helps identify and remove them.
Is my text data secure?
Yes. All processing happens directly in your browser. Your text never leaves your device or gets sent to any server.