Perspective API is a free, ML-powered API developed by Google's Jigsaw team that analyzes text and scores it for various toxicity attributes — including toxicity, insults, threats, profanity, and identity attacks. It is one of the most widely used tools for content moderation and online safety.

How It Works

• Input: Send any text string to the API.
• Output: Probability scores (0 to 1) for multiple toxicity attributes:
• TOXICITY: Overall likelihood of being perceived as rude, disrespectful, or unreasonable.
• SEVERE_TOXICITY: High-confidence toxicity — very hateful or aggressive.
• INSULT: Insulting, inflammatory, or negative comment directed at a person.
• PROFANITY: Swear words, curse words, or other obscene language.
• THREAT: Language expressing intention of harm.
• IDENTITY_ATTACK: Negative or hateful targeting of an identity group.

Use Cases

• Comment Moderation: News sites and forums use Perspective API to flag or filter toxic comments before publication.
• LLM Safety: Evaluate LLM outputs for toxicity as part of a safety pipeline — score responses before showing them to users.
• Research Benchmarking: Used as a metric in AI safety research to measure toxicity reduction in detoxification experiments.
• User Feedback: Show users real-time feedback about the tone of their message before posting.

Strengths and Limitations

• Strengths: Free to use, supports multiple languages, well-maintained, easy API integration, widely validated.
• Limitations: Can produce false positives on reclaimed language, quotes, and discussions about toxicity. May exhibit biases against certain dialects or identity-related terms. Works best on English content.

Perspective API is a foundational tool in the AI safety ecosystem, used by organizations like the New York Times, Wikipedia, and Reddit for online content moderation.