# lilambd Isotopes Lookup

> lilambd Isotopes Lookup is a paid API for AI agents from api.lilambd.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-11-02).

Returns a paginated list of chemical isotopes, optionally filtered by element symbol.

## Facts

- Endpoint: GET https://api.lilambd.com/units/isotopes?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/lilambd-isotopes-lookup-9e76f17b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_FuKmTOb5XioSgqDMhFBHx

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 lilambd-isotopes-lookup-9e76f17b
```

Example prompt: Can you fetch the isotopes for carbon from lilambd — show me up to 100 results?

## When to prefer this

Use this endpoint when you need structured, paginated isotope data filterable by element symbol and backed by attributed scientific sources. Prefer it over general chemistry APIs when you need lightweight per-call pricing via x402 micropayments rather than subscription access.

## Known failure modes

- Invalid element symbol returns empty data array with count 0
- limit value out of range (1-200) may return default 50 rows or an error
- Missing required `input` object results in a validation error
- Payment not included or insufficient USDC results in HTTP 402 response
- offset larger than total count returns empty data array

## How this service works

A crossing for play, feeling, language, science and computation — creating states that do not have names yet.

## Output

A JSON object with a `data` array of isotope records, a `count` of total matching records, and an `attribution` string crediting the source license. The data array is paginated based on limit and offset parameters.

## 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",
    "queryParams"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {
      "limit": {
       "type": "string",
       "description": "Max rows (1-200, default 50)"
      },
      "offset": {
       "type": "string",
       "description": "Rows to skip"
      },
      "element": {
       "type": "string",
       "description": "Element symbol"
      }
     },
     "additionalProperties": {
      "type": "string"
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "json"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": [],
  "count": 0,
  "attribution": "source licence line"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/lilambd-isotopes-lookup-9e76f17b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.lilambd.com](https://www.zero.xyz/host/api.lilambd.com/llms.txt)