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Yahoo Finance Japan — forum comments API (reverse-engineered)

Status: captured and verified with a plain HTTP client (2026-07-03, via headless Chromium network capture + urllib reproduction). No browser needed at runtime.

Endpoint

GET https://finance.yahoo.co.jp/bff-quote-stocks/v1/ajax/bbs/comment?code={CODE}&size={N}[&mid={CURSOR}]
  • code — bare stock code, no market suffix: 285A, 7203 (the page URL uses 285A.T, the API does not).
  • size — comments per call. 20 is what the site uses; 50 verified working.
  • mid — pagination cursor, a comment number (part). Omit for the newest page. Inclusive: mid=1273352 returns items starting at part 1273352 — dedupe by part when paging (comment numbers also have gaps from deletions).

Required headers (all three, else HTTP 400)

Header Value
x-jwt-token short-lived JWT extracted from the forum page HTML (see below)
referer https://finance.yahoo.co.jp/quote/{CODE}.T/forum
user-agent any realistic browser UA

Cookies (A/XA/B/XB) are set by the page fetch; keep a cookie jar across the two requests (verified working with them; not tested without).

Token acquisition

The JWT sits in the forum page HTML inside escaped embedded JSON as jwtToken\":\"eyJ...\". Payload is only {"exp": <unix>} (~2h validity, HS256). Flow: 1 GET of the page per CLI run → regex out the token → call the API.

Extraction regex (against raw HTML): jwtToken\\":\\"([^"\\]+) Fallback: eyJhbGciOiJIUzI1NiJ9\.[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+

Response shape

{
  "isSuccess": true,
  "response": {
    "categoryId": "1835673",
    "threadId": "3cbb9fa0a454194f0d07b74acd145222",
    "totalSize": 1273235,          // ≈ newest comment number, not an exact count
    "isError": false,
    "items": [
      {
        "part": 1273154,           // comment number (No.xxxxxxx), descending
        "userId": "d5e3b9bd...",   // stable hash
        "userIcon": "https://s.yimg.jp/...png",
        "dispname": "しろうと",     // display name (not masked, unlike page render)
        "infoLink": "https://finance.yahoo.co.jp/cm/personal/history/comment?user=...",
        "title": "アップルが中国製メモリーの調達&hellip;",   // truncated, HTML entities
        "body": "<span data-themeid=\"1212\">アップル</span>が...", // HTML: strip tags, unescape entities
        "postDate": "2026/7/3 7:32",
        "good": 8,                 // 「参考になりましたか？」はい
        "bad": 4                   //                       いいえ
      }
    ]
  }
}

Notes for implementation

  • body is HTML — strip tags (<span data-themeid>, <a>) and unescape entities for terminal display.
  • No per-comment sentiment field. The 買いたい tags seen on the page are a thread-level sentiment poll (e.g. 強く買いたい 26.83%、買いたい 2.44%) rendered in an _EvaluationGraph element in the page HTML. Optional nice-to-have: parse it from the page we already fetch for the JWT and print it as a header line. → Comment.sentiment will be None from this API.
  • Comment permalink: https://finance.yahoo.co.jp/quote/{CODE}.T/forum has no per-comment anchor confirmed yet; infoLink links to the author's history instead.

Capture method (for future re-verification)

Playwright headless Chromium, page.on("response") filtered to xhr/fetch, auto-scroll to trigger infinite scroll. Script preserved conceptually in this doc's git history; re-run if the endpoint starts returning 400 with valid tokens (signature/header change).

BBS comment ranking (掲示板投稿数ランキング)

Status: captured and verified with a plain HTTP client (2026-07-03, headless capture + urllib reproduction).

Source

GET https://finance.yahoo.co.jp/stocks/ranking/bbs?market=all&term={daily|weekly|monthly}&page={1,2,...}
  • No XHR/JSON API exists — the page fires only ad/tracking requests. The table is server-rendered with the data embedded in window.__PRELOADED_STATE__ (a JS assignment inside a <script>; parse with json.JSONDecoder().raw_decode starting after window.__PRELOADED_STATE__ =).
  • No JWT, no cookies needed — a plain GET with a browser User-Agent works (verified for monthly page 2).
  • 50 rows per page; daily/weekly had totalSize: 95, monthly 93 (~2 pages).

Embedded state shape

state["mainRankingList"]:

{
  "results": [
    {
      "rank": "1",                       // string
      "stockCode": "285A",
      "marketName": "東証PRM",
      "stockName": "キオクシアホールディングス(株)",
      "detailLink": "https://finance.yahoo.co.jp/quote/285A.T",
      "bbsUrl": "https://finance.yahoo.co.jp/quote/285A.T/forum",
      "savePrice": "83,300",             // display string, comma separators
      "date": "15:30",                   // price timestamp
      "rankingResult": { "bbsContents": { "updateDateTime": "2026/07/03 19:03" }, ...all-null fields... }
    }
  ],
  "paging": { "hasNext": true, "totalPage": 2, "totalSize": 95, "page": 1, "size": 50,
              "startIndex": 1, "endIndex": 50, "displayedPageNumbers": [1, 2] }
}

Notes: the ranking does NOT expose post counts — order + bbsContents.updateDateTime (last BBS activity) is all there is. savePrice and rank are strings. Fixture: tests/fixtures/ranking_state.json (one real mainRankingList, 50 entries).