What each classifier actually does (and the marketing copy you should ignore)
**OpenAI omni-moderation-latest** is, as of June 2026, the most capable free moderation endpoint on the market. Per https://platform.openai.com/docs/guides/moderation, it returns 13 category scores plus an overall flag in a single JSON call, accepts text or image inputs, and works in 40-plus languages with materially better non-English accuracy than text-moderation-007. The tagline to ignore is 'replace your entire trust-and-safety stack.' It is a classifier, not a policy engine — you still need rate-limiting, appeals, human review, and audit logging on top.
**OpenAI text-moderation-007** is the legacy text-only endpoint, still supported and free per https://platform.openai.com/docs/models/moderation. It uses the 11-category text taxonomy that shipped in 2022 (Markov et al., https://arxiv.org/abs/2208.03274). It has been functionally superseded by omni-moderation-latest for all new builds — non-English accuracy is worse and it cannot handle images. Use it only for pinned deployments that need deterministic behavior.
**Google Jigsaw Perspective API** at https://perspectiveapi.com/ is the longest-running production moderation service on this list — live since 2017 with more documented field experience than any other classifier here. It returns scores across six production attributes (TOXICITY, SEVERE_TOXICITY, IDENTITY_ATTACK, INSULT, PROFANITY, THREAT) plus experimental attributes. The marketing copy to ignore: Perspective is not 'free for all use.' It is free for non-commercial use under a 1 QPS default quota — commercial use or higher QPS requires a formal request at https://developers.perspectiveapi.com/s/docs-get-started.
**AWS Comprehend Toxicity Detection** lives inside the broader Comprehend NLP service (https://aws.amazon.com/comprehend/) and bills per character per https://aws.amazon.com/comprehend/pricing/. It returns scores across seven categories: HATE_SPEECH, GRAPHIC, HARASSMENT_OR_ABUSE, SEXUAL, VIOLENCE_OR_THREAT, INSULT, PROFANITY. The honest gap as of June 2026: the Comprehend Toxicity API is English-only. Multilingual workloads need Comprehend's language detection in front and another classifier for non-English, which adds latency and complexity.
**Azure AI Content Safety** at https://azure.microsoft.com/en-us/products/ai-services/ai-content-safety is Microsoft's purpose-built moderation product. It returns four core harm categories — Hate, Sexual, Violence, Self-Harm — each on a 0-7 severity scale. On top of that, Azure ships Prompt Shields (dedicated jailbreak/indirect-injection detection), Protected Material detection for copyrighted text and code, and a Groundedness detector for RAG outputs. The four-category core looks small versus OpenAI's 13, but the severity scale is easier to threshold and the ancillary detectors are unique to Azure.
**Hugging Face RoBERTa hate-speech models** — most cited being facebook/roberta-hate-speech-dynabench-r4-target at https://huggingface.co/facebook/roberta-hate-speech-dynabench-r4-target — are the open-weight reference for self-hosted moderation. The model is small (110M parameters), runs on a T4 GPU at sub-50ms latency, ships under a permissive license. What 'free moderation' posts skip: a single checkpoint covers one task (binary hate in English); matching OpenAI's category breadth needs an ensemble. Self-hosting trades vendor cost for engineering cost.