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Topics form a tree. Broad categories like Politics and Business contain subtopics like politics/elections and business/technology. Episodes are classified into topics automatically — fetch the taxonomy to power category navigation, route episodes to topic-specific feeds, or filter content by interest.
Available to MCP agents as particle_topic_browse.

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Browse the taxonomy

Top-level topics: 
curl "https://api.particle.pro/v1/topics?limit=10" \
  -H "X-API-Key: $PARTICLE_API_KEY"
Response (truncated)
{
  "data": [
    { "id": "FMABRApV", "name": "Society",     "slug": "society",     "ancestry_path": "E-sJ7" },
    { "id": "4FZ5KFM",  "name": "Government",  "slug": "government",  "ancestry_path": "Qcqm_" },
    { "id": "4FaC4H9",  "name": "Business",    "slug": "business",    "ancestry_path": "gWDfW" },
    { "id": "4FZ4EFh",  "name": "Politics",    "slug": "politics",    "ancestry_path": "GtizK" },
    { "id": "4K6dD5X",  "name": "Media",       "slug": "media",       "ancestry_path": "cbYxV" }
    // …
  ]
}
The ancestry_path is an opaque hash-based path used for programmatic ancestor filtering. Slugs follow a parent/child convention for subtopics (e.g. politics/elections). Get direct children of a topic by passing parent_id: 
# Subtopics under Politics
curl "https://api.particle.pro/v1/topics?parent_id=4FZ4EFh" \
  -H "X-API-Key: $PARTICLE_API_KEY"
Response (truncated)
{
  "data": [
    { "id": "4FZ4EFi",  "name": "International Relations", "slug": "politics/international-relations", "ancestry": "Politics" },
    { "id": "4FZ53X4",  "name": "Elections",               "slug": "politics/elections",               "ancestry": "Politics" },
    { "id": "FMEs52mJ", "name": "Political Parties",       "slug": "politics/political-parties",       "ancestry": "Politics" },
    { "id": "GIO2VHkb", "name": "Political Figures",       "slug": "politics/political-figures",       "ancestry": "Politics" }
    // …
  ]
}

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Get a single topic

The topic detail endpoint accepts any of three identifier forms in the path:
  • The encoded id returned by the list endpoint (e.g. 4FZ4EFh)
  • The full slug, including multi-level slugs with / (e.g. politics/elections)
  • The ancestry_path hash (e.g. GtizK, Qcqm_)
curl "https://api.particle.pro/v1/topics/4FZ4EFh" \
  -H "X-API-Key: $PARTICLE_API_KEY"
Response
{
  "id": "4FZ4EFh",
  "name": "Politics",
  "slug": "politics",
  "ancestry_path": "GtizK",
  "total_children": 27601,
  "children": [
    { "id": "4FZ4EFi",  "name": "International Relations", "slug": "politics/international-relations", "ancestry": "Politics", "ancestry_path": "GtizKFabWL" },
    { "id": "4FZ53X4",  "name": "Elections",               "slug": "politics/elections",               "ancestry": "Politics", "ancestry_path": "GtizKFGV8r" }
    // … up to 100 entries, ordered by prominence
  ]
}
Response fields:
  • ancestors — array of topic names from root to parent. Absent for root topics.
  • ancestry — single human-readable breadcrumb string. Absent for root topics.
  • total_children — total number of direct child topics. Always present (0 for leaves).
  • children — the top direct children ordered by prominence (url_cluster_count descending, ties broken by name). Capped at 100; when total_children exceeds 100, paginate the full set via /v1/topics?parent_id={id}.

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Topics for an episode

Podcast episodes are classified into topics automatically. Fetch the topics for any episode: 
curl "https://api.particle.pro/v1/podcasts/episodes/{episode_id}/topics" \
  -H "X-API-Key: $PARTICLE_API_KEY"
See Episodes → Topics for the integrated discovery flow.
  • Entities — the people, organizations, and places counterpart to topics
  • Episodes — filter by topic, then drill into transcripts and clips