1 endpoint · 9 indexes · 9 answering · 445,348 listings behind the headline · no key

The whole masthead, as one document

One GET. No key, no account, no rate limit, and CORS open so a browser can call it.

/api/index.jsonOpen it

1{
2  "masthead": "Toolproof",
3  "methodology": "https://toolproof.kynth.studio/methodology",
4  "methodology_version": "1.0",
5  "license": "CC-BY-4.0",
6  "meta": {
7    "indexes": 9,
8    "readable": 9,
9    "unreadable": 0
10  },
11  "headline": {
12    "claim": "share of measured agent-skill listings that do not load",
13    "measured": 445348,
14    "failing": 43199,
15    "share": 0.097,
16    "as_of": "2026-08-14T07:52:38.608+00:00"
17  },
18  "indexes": [
19    {
20      "slug": "skillworks",
21      "name": "SkillWorks",
22      "ok": true,
23      "source": "https://skillworks.kynth.studio/api/stats",
24      "headline": {
25        "value": 445348,
26        "label": "listings read from source"
27      },
28      "rows": [
29        {
30          "label": "that do not load",
31          "value": "43,199"
32        },
33        {
34          "label": "share failing",
35          "value": "9.7%"
36        },
37        {
38          "label": "repositories",
39          "value": "21,983"
40        }
41      ],
42      "as_of": "2026-08-14T07:52:38.608+00:00",
43      "stale": false
44    },
45    {
46      "slug": "stillshipping",
47      "name": "StillShipping",
48      "ok": true,
49      "source": "https://stillshipping.kynth.studio/api/stats",
50      "headline": {
51        "value": 333,
52        "label": "tools tracked"
53      },
54      "rows": [
55        {
56          "label": "maintained",
57          "value": "293"
58        },
59        {
60          "label": "slowing",
61          "value": "16"
62        },
63        {
64          "label": "dead",
65          "value": "24"
66        }
67      ],
68      "as_of": "2026-08-14T06:19:42.233+00:00",
69      "stale": null
70    }
71  ]
72}

Truncated to two indexes above; the live document carries all 9. It was generated from the same read the endpoint serves, so this sample cannot drift from the response.

What the document promises

Nine entries, always: An index that could not be read appears with ok: false and the reason, and is counted in meta.unreadable. The array never silently shrinks — a consumer must be able to tell a missing index from an index that measured nothing.
No stored figures: Every value is fetched from the index that measured it when the document is built. There is no fallback constant anywhere in this codebase, so a figure here is either current or absent.
Provenance on every row: source is the public URL the figure came from — call it yourself and you should get the same number. as_of is the run that produced it and fetched_at is when we read it. Those are different dates and both matter.
The method travels with the data: methodology and methodology_version are in the payload rather than on a page a machine will not read. A figure without the method behind it is an assertion.
Staleness is passed through: Where an index publishes its own stale flag, it is forwarded untouched. We do not decide on its behalf whether its pipeline is behind.

Using it

Quote any figure with attribution to Toolproof and the date of the run it came from. The method text is published under CC BY 4.0. If a number here is wrong, it gets corrected and the correction is dated on the methodology page whichever direction it moves.

Each of the nine also answers on its own domain — the source field on every row is the exact URL, and none of them needs a key either. Toolproof does not sit in front of them; it reads them the same way you would.

Open index.json The method behind it

The whole masthead, as one document

What the document promises

Using it

Built for the same person as Toolproof