# Particle Pro – Get Topic

> Particle Pro – Get Topic is a paid API for AI agents from api.particle.pro, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Retrieves a single topic node with its breadcrumb ancestor chain and top direct child topics ranked by prominence.

## Facts

- Endpoint: GET https://api.particle.pro/v1/topics/:id
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/particle-pro-get-topic-b886b528
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vpPUpzlL4VjD_AN-mRuHD

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability particle-pro-get-topic-b886b528
```

Example prompt: What are the main sub-topics under 'technology/artificial-intelligence' in Particle Pro's topic hierarchy, including its breadcrumb ancestors?

## When to prefer this

Use this endpoint when you need to understand the hierarchical context of a specific topic — its parent lineage and prominent children — as opposed to listing all topics or searching articles. Prefer it over a search endpoint when you already have a topic ID or well-known ancestry slug. It is ideal for building navigation trees, editorial classification tools, or ad-targeting context systems that require structured topic taxonomy data.

## Known failure modes

- Topic ID or slug not found — returns 404 with no topic data
- Malformed slug or path hash — returns 400 bad request
- Payment not fulfilled via x402 protocol — returns 402 Payment Required
- Rate limit exceeded — returns 429 too many requests
- Ambiguous slug matches multiple topics — may return unexpected topic

## How this service works

Get a topic. Returns a single topic with breadcrumb ancestors and the top direct children by prominence.

## Output

Returns a single topic object including its unique ID, name, breadcrumb ancestor chain (showing the full path from root to the topic), and a ranked list of the most prominent direct child topics. This gives a complete view of where a topic sits in the content taxonomy and what sub-topics it contains.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "pathParams": {
     "type": "object",
     "required": [
      "id"
     ],
     "properties": {
      "id": {
       "type": "string",
       "description": "Topic ID, ancestry slug (e.g., technology/artificial-intelligence), or ancestry path hash"
      }
     }
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/particle-pro-get-topic-b886b528/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.particle.pro](https://www.zero.xyz/host/api.particle.pro/llms.txt)