# Accelerometer AI-Progress Delta Feed (x402)

> Accelerometer AI-Progress Delta Feed (x402) is a paid API for AI agents from x402-accelerometer-feed.fly.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-19).

Returns per-source changes across 129 AI-progress and technology time series between two dated snapshots, paid via x402/USDC.

## Facts

- Endpoint: GET https://x402-accelerometer-feed.fly.dev/delta/%7Bfrom%7D/%7Bto%7D
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-19
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/accelerometer-ai-progress-delta-feed-x402-4e030f35
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_OD_z6d2NEziZ9DXTBW4pr

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 accelerometer-ai-progress-delta-feed-x402-4e030f35
```

Example prompt: Show me what changed across the 129 AI-progress and technology time series between July 12 2026 and September 16 2026 — I want to see which metrics moved and by how much.

## When to prefer this

Choose this endpoint when you need to quantify change — not just current state — across AI-progress metrics between two specific dates. It is the right choice for trend analysis, progress reports, anomaly detection, and tracking specific series like benchmark scores, compute costs, model pricing, or prediction market odds over a defined interval. Prefer the latest-snapshot sibling endpoint if you only need current values, or the specific-date sibling if you want a full snapshot without diffing.

## Known failure modes

- Invalid or non-existent snapshot date IDs return an error or empty result
- Date range with no available snapshots yields zero moved series
- Network timeout on the fly.dev host
- x402 payment failure if USDC balance on Base is insufficient
- Malformed date format in {from} or {to} path parameters causes a request error
- Future dates beyond available snapshot range return no data

## How this service works

Timestamped per-source snapshots of 129 public AI-progress and technology time series (frontier benchmark scores, compute trends, AGI prediction-market odds, model pricing, AI stocks and crypto, energy, space, robotics, biomed, research output). No composite score. Paid with USDC on Base via x402.

## Output

A JSON object containing two snapshot references (from/to run timestamps and snapshot IDs), the count of series that moved (n_moved), and an array of per-source records each with absolute and percentage delta, the from/to values and dates, unit, domain, metric label, and a flag indicating whether a new observation was added. The composite field is always null (no composite score). Total series count is 129.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "to": {
   "run_at": "2026-09-16T12:25:28.530204+00:00",
   "snapshot_id": "2026-09-16"
  },
  "from": {
   "run_at": "2026-07-12T14:00:05.754191+00:00",
   "snapshot_id": "2026-07-12"
  },
  "kind": "delta",
  "n_moved": 76,
  "sources": [
   {
    "id": "agents.x402_services_count",
    "to": {
     "date": "2026-09-16",
     "value": 2865
    },
    "from": {
     "date": "2026-07-12",
     "value": 1779
    },
    "unit": "count",
    "domain": "agents",
    "metric": "x402 pay-per-request services (agentic.market)",
    "delta_abs": 1086,
    "delta_pct": 61.0455,
    "new_observation": true
   },
   {
    "id": "autonomy.metr_time_horizon_50",
    "to": {
     "date": "2025-04-16",
     "value": 112.230447
    },
    "from": {
     "date": "2025-04-16",
     "value": 112.230447
    },
    "unit": "minutes",
    "domain": "autonomy",
    "metric": "METR frontier task-completion horizon @50% (minutes)",
    "delta_abs": 0,
    "delta_pct": 0,
    "new_observation": false
   }
  ],
  "composite": null,
  "n_sources": 129,
  "schema_version": "0.2"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/accelerometer-ai-progress-delta-feed-x402-4e030f35/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-accelerometer-feed.fly.dev](https://www.zero.xyz/host/x402-accelerometer-feed.fly.dev/llms.txt)