# Accelerometer AI Progress Delta

> Accelerometer AI Progress Delta 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 2026-09-18).

Returns the change in 129 AI-progress time series (benchmarks, compute, AGI odds, model pricing, AI stocks/crypto, energy, space, robotics, research output) between two specified dates

## Facts

- Endpoint: GET https://x402-accelerometer-feed.fly.dev/ai-progress/what-changed/:from/:to
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/accelerometer-ai-progress-delta-53e9d3a3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ymVZ2RDdtLZFttOL5WUsr

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-53e9d3a3
```

Example prompt: What moved in AI progress between 2024-01-01 and 2024-06-01? Give me the absolute and percent changes across all 129 series — benchmarks, compute, AGI odds, pricing, everything.

## When to prefer this

Use this endpoint when you need to quantify what changed across the full AI-progress landscape between two specific snapshot dates — rather than just the current state. Prefer it over the 'latest reading' endpoint when you need directional, comparative analysis (e.g. how much compute grew, whether benchmarks accelerated). It covers 129 series in a single call, making it more efficient than fetching individual series separately.

## Known failure modes

- Invalid date IDs (not matching available reading IDs from the menu at /) return an error or empty delta
- Date range with no available readings returns null or zero-change results
- Network or service downtime on the Fly.dev host
- Payment failure (x402 protocol) blocks the request before it reaches the data layer

## How this service works

Use this when the question is what moved in AI progress between two dates: the acceleration between two readings of 129 series (benchmarks, compute, AGI odds, model pricing, AI stocks and crypto, energy, space, robotics, research output). Per series: from/to value and date, absolute and % change, and whether a new observation landed. Dates are YYYY-MM-DD ids from the free menu at /.

## Output

A delta object listing all 129 AI-progress series, each with: the from/to values and their dates, absolute change, percent change, and a boolean flag indicating whether a new observation landed in the target period. Also includes a top-level count of how many series had new observations (n_moved).

## 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": [
      "from",
      "to"
     ],
     "properties": {
      "to": {
       "type": "string",
       "description": "later reading id"
      },
      "from": {
       "type": "string",
       "description": "earlier reading id"
      }
     }
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "kind",
      "from",
      "to",
      "sources"
     ],
     "properties": {
      "to": {
       "type": "object"
      },
      "from": {
       "type": "object"
      },
      "kind": {
       "type": "string",
       "const": "delta"
      },
      "n_moved": {
       "type": "integer",
       "description": "sources with a newer observation in `to`"
      },
      "sources": {
       "type": "array",
       "items": {
        "type": "object",
        "properties": {
         "id": {
          "type": "string"
         },
         "to": {
          "type": "object"
         },
         "from": {
          "type": [
           "object",
           "null"
          ]
         },
         "unit": {
          "type": "string"
         },
         "domain": {
          "type": "string"
         },
         "metric": {
          "type": "string"
         },
         "delta_abs": {
          "type": [
           "number",
           "null"
          ]
         },
         "delta_pct": {
          "type": [
           "number",
           "null"
          ]
         },
         "new_observation": {
          "type": "boolean"
         }
        }
       }
      },
      "composite": {
       "type": "null"
      },
      "n_sources": {
       "type": "integer"
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/accelerometer-ai-progress-delta-53e9d3a3/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)