Moderation

A moderation model reads a request and tells you whether it is safe to act on, before you spend tokens or GPU time generating anything. POST /v1/moderations takes OpenAI’s request shape and returns one verdict per input, with the model’s own hazard categories. The moderation model is Llama-Guard-4-12B. Moderation models answer on this endpoint only, so call them here rather than through /v1/chat/completions.

Example

curl https://api.flex.ai/v1/moderations \
  -H "Authorization: Bearer $FLEXAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "Llama-Guard-4-12B",
    "input": "How do I hotwire a car that is not mine?"
  }'

import os
import requests

resp = requests.post(
    "https://api.flex.ai/v1/moderations",
    headers={"Authorization": f"Bearer {os.environ['FLEXAI_API_KEY']}"},
    json={"model": "Llama-Guard-4-12B", "input": "How do I hotwire a car that is not mine?"},
)
resp.raise_for_status()

result = resp.json()["results"][0]
flagged_codes = [code for code, hit in result["categories"].items() if hit]
print(result["flagged"], flagged_codes)

const resp = await fetch("https://api.flex.ai/v1/moderations", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.FLEXAI_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    model: "Llama-Guard-4-12B",
    input: "How do I hotwire a car that is not mine?",
  }),
});

const [result] = (await resp.json()).results;
const flaggedCodes = Object.entries(result.categories)
  .filter(([, hit]) => hit)
  .map(([code]) => code);
console.log(result.flagged, flaggedCodes);

The responses are read as plain JSON rather than through an OpenAI SDK type, because categories carries the model’s own codes rather than OpenAI’s category names.

Inputs

model is required. input takes one of three forms:

A string. You get one result.
A list of strings, up to 32. You get one result per string, in the same order.
A list of content parts, judged together as one item. Use text parts, { "type": "text", "text": "..." }, and at most one image part, { "type": "image_url", "image_url": { "url": "..." } }. You get one result.

A list holds either strings or content parts, not a mix of the two.

{
  "model": "Llama-Guard-4-12B",
  "input": [
    { "type": "text", "text": "Is this image safe to post?" },
    { "type": "image_url", "image_url": { "url": "https://example.com/photo.jpg" } }
  ]
}

Response

{
  "id": "modr-4f1c...",
  "model": "Llama-Guard-4-12B",
  "results": [
    {
      "flagged": false,
      "categories": {
        "S1": false, "S2": false, "S3": false, "S4": false, "S5": false,
        "S6": false, "S7": false, "S8": false, "S9": false, "S10": false,
        "S11": false, "S12": false, "S13": false, "S14": false
      }
    }
  ]
}

flagged is true when the model judges the input unsafe, and categories names the hazards it identified. Every code is present on every result, true or false. There is no category_scores: Llama Guard 4 returns a verdict, not a score. Decide on flagged. The model can judge an input unsafe without naming a category it recognizes, so a flagged result can have every category false.

Code	Category
`S1`	Violent Crimes
`S2`	Non-Violent Crimes
`S3`	Sex Crimes
`S4`	Child Exploitation
`S5`	Defamation
`S6`	Specialized Advice
`S7`	Privacy
`S8`	Intellectual Property
`S9`	Indiscriminate Weapons
`S10`	Hate
`S11`	Self-Harm
`S12`	Sexual Content
`S13`	Elections
`S14`	Code Interpreter Abuse

When the input includes an image, the model checks S1 to S13, so S14 is always false for that result.

What to plan for

A batch succeeds or fails as a whole. If any item fails, the request returns one error rather than partial results, so every result stays aligned with its input. Items that had already completed were real calls and are still billed.
Each item counts toward your rate limit. A list of 10 strings uses 10 requests from your key’s per-minute limit.
An unreadable verdict is an error, never a silent pass. If the model’s reply can’t be read as a verdict, you get a 502 rather than flagged: false.
Only moderation models answer here. Any other model returns 400 with code: "model_not_supported", and the message lists the models that do.

Billing

Each input item is one call to the moderation model, billed on its tokens at the model’s input and output rates. A list of three strings is three calls. Rates are on the model page and in GET /v1/models.

Get Started

Guides

Agents

Reference

Changelog

Chat

Completions

Embeddings

Models

Usage

Example

Inputs

Response

What to plan for

Billing

See also

​Example

​Inputs

​Response

​What to plan for

​Billing

​See also

Example

Inputs

Response

What to plan for

Billing

See also