# Delx Base64 Size Estimate

> Delx Base64 Size Estimate is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).

Estimates the decoded byte size of a base64-encoded string without performing a full decode, returning a deterministic byte count in JSON

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/base64-size-estimate
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-base64-size-estimate-f5ad6e44
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bFFruZ5tGDj1ZY4EAFQAk

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 delx-base64-size-estimate-f5ad6e44 -d '<json body>'
```

Example prompt: Before I decode this base64 string, can you estimate how many bytes it will be when decoded? Here's the value: 'SGVsbG8gV29ybGQhIFRoaXMgaXMgYSB0ZXN0Lg=='

## When to prefer this

Choose this endpoint when you need a fast, cheap, stateless estimate of decoded base64 byte size without the overhead of a full decode — ideal for preflight checks, memory budgeting, or size validation before committing to a full decode operation. Prefer this over decoding the string yourself when operating in constrained environments or when you want a deterministic, machine-readable result at minimal cost ($0.001 USDC).

## Known failure modes

- Invalid or malformed base64 string may result in an error or inaccurate estimate
- Empty input string returns zero or an error response
- Base64 strings with incorrect padding may produce unreliable size estimates
- Payment failure via x402 will prevent execution and return a 402 response

## How this service works

Estimate decoded byte size of a base64 string without full decode — first-party local utility for agent preflight and proven micro-utils expansion. Returns deterministic machine-readable JSON for $0.001 USDC via x402 on Base. Execution is first-party, local-only, stateless, and memory-only with no paid upstream, no input retention, no web search, no live RPC, and no mediagen. Results are advisory; the caller owns authorization, budgets, and production controls. Sibling of Delx routes that alrea…

## Output

A JSON object containing the estimated decoded byte size of the provided base64 string, computed deterministically without performing a full decode. The result is advisory and returned as a machine-readable numeric value representing bytes.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "base64": {
   "type": "string",
   "description": "Input field: base64."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "schema": "delx/util-base64-size-estimate/v1",
  "padding": 1,
  "encoded_chars": 8,
  "decoded_bytes_estimate": 5
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-base64-size-estimate-f5ad6e44/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)