---
title: "Documentación API y CLI: Node, Python, Go y PHP | SingleFax"
description: "Envía faxes desde tu servidor con la API REST y CLI npm de SingleFax. Crédito prepago, claves API, OpenAPI y ejemplos curl, Node, Python, Go y PHP."
canonical_url: "https://singlefax.com/es/desarrolladores"
meta:
  "og:description": "Envía faxes desde tu servidor con la API REST y CLI npm de SingleFax. Crédito prepago, claves API, OpenAPI y ejemplos curl, Node, Python, Go y PHP."
  "og:image": "https://singlefax.com/_og/s/o_05e5c6ed0811c97c.jpeg"
  "og:image:alt": "Documentación API y CLI: Node, Python, Go y PHP"
  "og:image:height": "630"
  "og:image:type": image/jpeg
  "og:image:width": "1200"
  "og:title": "Envía un fax desde tu servidor"
---

> Index of every page on this site: [llms.txt](https://singlefax.com/llms.txt)

[singlefax](https://singlefax.com/es)

[Enviar y recibir](https://singlefax.com/es/enviar-fax) [Para empresas](https://singlefax.com/es/para-empresas)Soluciones [Precios](https://singlefax.com/es/precios) [Blog](https://singlefax.com/es/blog)

<details>

<summary>Idioma</summary>



<a href="https://singlefax.com/developers">English</a><a href="https://singlefax.com/de/entwickler">Deutsch</a><a href="https://singlefax.com/fr/developpeurs">Français</a><a href="https://singlefax.com/it/sviluppatori">Italiano</a><a href="https://singlefax.com/zh-tw/%E9%96%8B%E7%99%BC%E4%BA%BA%E5%93%A1">繁體中文</a><a href="https://singlefax.com/pt-br/desenvolvedores">Português do Brasil</a><a href="https://singlefax.com/tr/gelistiriciler">Türkçe</a><a href="https://singlefax.com/ko/%EA%B0%9C%EB%B0%9C%EC%9E%90">한국어</a><a href="https://singlefax.com/ja/%E9%96%8B%E7%99%BA%E8%80%85%E5%90%91%E3%81%91">日本語</a><a href="https://singlefax.com/ar/%D8%A7%D9%84%D9%85%D8%B7%D9%88%D8%B1%D9%88%D9%86">العربية</a>

</details>

[Iniciar sesión](https://singlefax.com/es/iniciar-sesion)

REST · CLI · OpenAPI

# Documentación API y CLI de SingleFax

Clave API y crédito prepago. CLI oficial de npm o ejemplos REST en curl, Node, Python, Go y PHP. Las aplicaciones de chat deben usar MCP.

[Crear una clave API](https://singlefax.com/es/iniciar-sesion?redirect=/dashboard/api-keys) [CLI de npm](https://www.npmjs.com/package/@singlefax/cli) [OpenAPI](https://singlefax.com/openapi.json)

## CLI

`npx @singlefax/cli send FILE --to +E164`: envía Word, Excel, PDF o imagen original, sin convertir antes a PDF.

## REST

`POST /api/v1/faxes` con Bearer `sf_live_…` y `Idempotency-Key`.

## MCP para chat

Cursor, Claude, Codex, ChatGPT: OAuth, no clave API. [Instalar MCP](https://singlefax.com/es/agentes-ia).

## Inicio rápido

1. Crea una clave con permisos limitados en [Claves API](https://singlefax.com/es/iniciar-sesion?redirect=/dashboard/api-keys): `fax:send`, `fax:read`, `inbox:read`, `credits:read`.
2. Compra crédito en el panel o mediante `npx @singlefax/cli credits buy`.
3. Envía con la CLI de abajo o con `POST /api/v1/faxes`.

URL base `https://api.singlefax.com`, mismas rutas en `https://singlefax.com`. Las claves `sf_test_` no envían faxes reales. No las pongas en el navegador.

## CLI

Node 20 o superior. Configuración: `SINGLEFAX_API_KEY` o `~/.config/singlefax/config.json`. Envía el Word, Excel, PowerPoint, PDF, texto o imagen original; no conviertas antes. No sirve para MCP OAuth ni Stripe MPP.

terminalCopiar

```
export SINGLEFAX_API_KEY=sf_live_…

npx @singlefax/cli send ./document.docx --to +14155552671
npx @singlefax/cli send ./document.pdf --to +14155552671 --wait --json
```

quote, status, creditsCopiar

```
npx @singlefax/cli quote --to +14155552671 --pages 12
npx @singlefax/cli status <id>
npx @singlefax/cli list
npx @singlefax/cli numbers
npx @singlefax/cli numbers buy
npx @singlefax/cli credits
npx @singlefax/cli credits buy --dollars 20
```

## Enviar un fax

Una solicitud: documento en base64 y destino. PDF, Word, Excel, PowerPoint, texto o imágenes. `Idempotency-Key` es obligatorio. Reutilizar una clave con otro cuerpo devuelve 409.

curlJavaScriptPythonGoPHP

terminalCopiar

```
PDF_B64="$(base64 < document.pdf | tr -d '\n')"

curl -sS https://api.singlefax.com/api/v1/faxes \
  -H "Authorization: Bearer $SINGLEFAX_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d "{\"to\":\"+14155552671\",\"base64\":\"$PDF_B64\"}"
```

send.mjsCopiar

```
import { readFile } from 'node:fs/promises'
import { randomUUID } from 'node:crypto'

const api = 'https://api.singlefax.com'
const key = process.env.SINGLEFAX_API_KEY
const pdf = await readFile('./document.pdf')

const res = await fetch(`${api}/api/v1/faxes`, {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${key}`,
    'Content-Type': 'application/json',
    'Idempotency-Key': randomUUID(),
  },
  body: JSON.stringify({
    to: '+14155552671',
    base64: pdf.toString('base64'),
  }),
})
console.log(await res.json())
```

send.pyCopiar

```
import base64, json, os, urllib.request, uuid
from pathlib import Path

API = "https://api.singlefax.com"
KEY = os.environ["SINGLEFAX_API_KEY"]
pdf = Path("document.pdf").read_bytes()

req = urllib.request.Request(
    f"{API}/api/v1/faxes",
    data=json.dumps({
        "to": "+14155552671",
        "base64": base64.b64encode(pdf).decode(),
    }).encode(),
    headers={
        "Authorization": f"Bearer {KEY}",
        "Content-Type": "application/json",
        "Idempotency-Key": str(uuid.uuid4()),
    },
    method="POST",
)
with urllib.request.urlopen(req) as res:
    print(res.read().decode())
```

send.goCopiar

```
package main

import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
)

func main() {
	pdf, err := os.ReadFile("document.pdf")
	if err != nil {
		panic(err)
	}
	body, _ := json.Marshal(map[string]string{
		"to":     "+14155552671",
		"base64": base64.StdEncoding.EncodeToString(pdf),
	})
	req, _ := http.NewRequest("POST", "https://api.singlefax.com/api/v1/faxes", bytes.NewReader(body))
	req.Header.Set("Authorization", "Bearer "+os.Getenv("SINGLEFAX_API_KEY"))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Idempotency-Key", "send-document-1")
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	out, _ := io.ReadAll(res.Body)
	fmt.Println(res.Status, string(out))
}
```

send.phpCopiar

```
<?php
$pdf = base64_encode(file_get_contents('document.pdf'));
$ch = curl_init('https://api.singlefax.com/api/v1/faxes');
curl_setopt_array($ch, [
  CURLOPT_POST => true,
  CURLOPT_HTTPHEADER => [
    'Authorization: Bearer ' . getenv('SINGLEFAX_API_KEY'),
    'Content-Type: application/json',
    'Idempotency-Key: send-document-1',
  ],
  CURLOPT_POSTFIELDS => json_encode(['to' => '+14155552671', 'base64' => $pdf]),
  CURLOPT_RETURNTRANSFER => true,
]);
echo curl_exec($ch);
```

## Archivos grandes: subir y después enviar

La CLI crea un token de subida, carga los datos con PUT y envía con `uploadToken`. PUT también requiere Bearer. Es preferible a incluir un archivo grande en JSON. No conviertas antes a PDF.

curlJavaScriptPythonGoPHP

terminalCopiar

```
UPLOAD=$(curl -sS https://api.singlefax.com/api/v1/uploads \
  -H "Authorization: Bearer $SINGLEFAX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"contentType":"application/pdf"}')

UPLOAD_URL=$(printf '%s' "$UPLOAD" | python3 -c "import json,sys; print(json.load(sys.stdin)['uploadUrl'])")
TOKEN=$(printf '%s' "$UPLOAD" | python3 -c "import json,sys; print(json.load(sys.stdin)['uploadToken'])")

curl -sS -X PUT "$UPLOAD_URL" \
  -H "Authorization: Bearer $SINGLEFAX_API_KEY" \
  -H "Content-Type: application/pdf" \
  --data-binary @document.pdf

curl -sS https://api.singlefax.com/api/v1/faxes \
  -H "Authorization: Bearer $SINGLEFAX_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d "{\"to\":\"+14155552671\",\"uploadToken\":\"$TOKEN\"}"
```

upload-send.mjsCopiar

```
import { readFile } from 'node:fs/promises'
import { randomUUID } from 'node:crypto'

const api = 'https://api.singlefax.com'
const key = process.env.SINGLEFAX_API_KEY
const auth = { Authorization: `Bearer ${key}` }
const pdf = await readFile('./document.pdf')

const upload = await fetch(`${api}/api/v1/uploads`, {
  method: 'POST',
  headers: { ...auth, 'Content-Type': 'application/json' },
  body: JSON.stringify({ contentType: 'application/pdf', maxBytes: pdf.byteLength }),
}).then((r) => r.json())

await fetch(upload.uploadUrl, {
  method: 'PUT',
  headers: { ...auth, 'Content-Type': 'application/pdf' },
  body: pdf,
})

const fax = await fetch(`${api}/api/v1/faxes`, {
  method: 'POST',
  headers: {
    ...auth,
    'Content-Type': 'application/json',
    'Idempotency-Key': randomUUID(),
  },
  body: JSON.stringify({ to: '+14155552671', uploadToken: upload.uploadToken }),
}).then((r) => r.json())

console.log(fax)
```

upload\_send.pyCopiar

```
import json, os, urllib.request, uuid
from pathlib import Path

API = "https://api.singlefax.com"
KEY = os.environ["SINGLEFAX_API_KEY"]
pdf = Path("document.pdf").read_bytes()

def request(url, *, data=None, method="GET", headers=None, content_type="application/json"):
    req = urllib.request.Request(
        url,
        data=data,
        headers={
            "Authorization": f"Bearer {KEY}",
            "Content-Type": content_type,
            **(headers or {}),
        },
        method=method,
    )
    with urllib.request.urlopen(req) as res:
        return res.read()

upload = json.loads(request(
    f"{API}/api/v1/uploads",
    method="POST",
    data=json.dumps({"contentType": "application/pdf", "maxBytes": len(pdf)}).encode(),
))
request(upload["uploadUrl"], method="PUT", data=pdf, content_type="application/pdf")
fax = request(
    f"{API}/api/v1/faxes",
    method="POST",
    data=json.dumps({"to": "+14155552671", "uploadToken": upload["uploadToken"]}).encode(),
    headers={"Idempotency-Key": str(uuid.uuid4())},
)
print(fax.decode())
```

upload\_send.goCopiar

```
package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
)

func main() {
	key := os.Getenv("SINGLEFAX_API_KEY")
	pdf, err := os.ReadFile("document.pdf")
	if err != nil {
		panic(err)
	}

	upBody, _ := json.Marshal(map[string]any{"contentType": "application/pdf", "maxBytes": len(pdf)})
	upReq, _ := http.NewRequest("POST", "https://api.singlefax.com/api/v1/uploads", bytes.NewReader(upBody))
	upReq.Header.Set("Authorization", "Bearer "+key)
	upReq.Header.Set("Content-Type", "application/json")
	upRes, err := http.DefaultClient.Do(upReq)
	if err != nil {
		panic(err)
	}
	defer upRes.Body.Close()
	var upload struct {
		UploadToken string `json:"uploadToken"`
		UploadUrl   string `json:"uploadUrl"`
	}
	json.NewDecoder(upRes.Body).Decode(&upload)

	put, _ := http.NewRequest("PUT", upload.UploadUrl, bytes.NewReader(pdf))
	put.Header.Set("Authorization", "Bearer "+key)
	put.Header.Set("Content-Type", "application/pdf")
	if _, err := http.DefaultClient.Do(put); err != nil {
		panic(err)
	}

	sendBody, _ := json.Marshal(map[string]string{"to": "+14155552671", "uploadToken": upload.UploadToken})
	faxReq, _ := http.NewRequest("POST", "https://api.singlefax.com/api/v1/faxes", bytes.NewReader(sendBody))
	faxReq.Header.Set("Authorization", "Bearer "+key)
	faxReq.Header.Set("Content-Type", "application/json")
	faxReq.Header.Set("Idempotency-Key", "send-document-1")
	faxRes, err := http.DefaultClient.Do(faxReq)
	if err != nil {
		panic(err)
	}
	defer faxRes.Body.Close()
	out, _ := io.ReadAll(faxRes.Body)
	fmt.Println(string(out))
}
```

upload-send.phpCopiar

```
<?php
$key = getenv('SINGLEFAX_API_KEY');
$pdf = file_get_contents('document.pdf');

$ch = curl_init('https://api.singlefax.com/api/v1/uploads');
curl_setopt_array($ch, [
  CURLOPT_POST => true,
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer $key",
    'Content-Type: application/json',
  ],
  CURLOPT_POSTFIELDS => json_encode(['contentType' => 'application/pdf', 'maxBytes' => strlen($pdf)]),
  CURLOPT_RETURNTRANSFER => true,
]);
$upload = json_decode(curl_exec($ch), true);

$ch = curl_init($upload['uploadUrl']);
curl_setopt_array($ch, [
  CURLOPT_CUSTOMREQUEST => 'PUT',
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer $key",
    'Content-Type: application/pdf',
  ],
  CURLOPT_POSTFIELDS => $pdf,
  CURLOPT_RETURNTRANSFER => true,
]);
curl_exec($ch);

$ch = curl_init('https://api.singlefax.com/api/v1/faxes');
curl_setopt_array($ch, [
  CURLOPT_POST => true,
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer $key",
    'Content-Type: application/json',
    'Idempotency-Key: send-document-1',
  ],
  CURLOPT_POSTFIELDS => json_encode(['to' => '+14155552671', 'uploadToken' => $upload['uploadToken']]),
  CURLOPT_RETURNTRANSFER => true,
]);
echo curl_exec($ch);
```

## Referencia REST

| Método | Ruta | Autenticación | Notas |
| --- | --- | --- | --- |
| POST | /api/v1/faxes | fax:send | Idempotency-Key required. JSON { to, base64 \| uploadToken } or multipart file. |
| GET | /api/v1/faxes | fax:read | List. Query limit, offset. |
| GET | /api/v1/faxes/{id} | fax:read | Status including latest delivery attempt. |
| POST | /api/v1/faxes/quote | fax:read | { to, pages? \| base64? }, quote without charging. |
| POST | /api/v1/uploads | fax:send | Returns uploadToken + uploadUrl. PUT the bytes, then send with uploadToken. |
| GET | /api/v1/credits | credits:read | Prepaid balance. |
| POST | /api/v1/credits/checkout | credits:checkout | { amountCents }. Stripe Checkout for a credit pack. |
| GET | /api/v1/received-faxes | inbox:read | Inbound inbox list. Query limit, cursor. No transcripts in list. |
| GET | /api/v1/received-faxes/{id} | inbox:read | Inbound detail with bounded transcript slice. HIPAA Secure content is omitted. |
| GET | /api/v1/numbers | fax:read | Active fax numbers. |
| POST | /api/v1/numbers | credits:checkout | { sku?, country?, state? }, default inbound\_30day. Returns checkoutUrl + reserved phoneNumber. |
| GET | /api/v1/skus | public | Catalog. Same shape as MCP list\_skus. |
| POST | /api/v1/checkout | credits:checkout | { sku }, credit\_pack, inbound, subscriptions, lifetime. |

Esquemas completos: [openapi.json](https://singlefax.com/openapi.json). Cambios incompatibles: [política de versiones](https://singlefax.com/es/versionado), Sunset de 90 días. HTTP 402 en esta API significa saldo insuficiente. MPP 402 solo se usa en `POST /api/v1/machine/faxes`.

## Webhooks

Eventos firmados `fax.queued`, `fax.delivered`, `fax.failed` y `credits.low_balance`. Verifica `SingleFax-Signature`, `t=,v1=`, con el cuerpo original. HMAC-SHA256 de `timestamp.payload`. Añade el endpoint en [webhooks del panel](https://singlefax.com/es/iniciar-sesion?redirect=/dashboard/webhooks).

JavaScriptPython

verify.mjsCopiar

```
import { createHmac, timingSafeEqual } from 'node:crypto'

export function verifySingleFaxSignature(rawBody, signatureHeader, secret, toleranceSeconds = 300) {
  const parts = Object.fromEntries(signatureHeader.split(',').map((kv) => kv.split('=')))
  const timestamp = Number(parts.t)
  if (!Number.isFinite(timestamp) || !parts.v1) return false
  if (Math.abs(Math.floor(Date.now() / 1000) - timestamp) > toleranceSeconds) return false
  const expected = createHmac('sha256', secret).update(`${timestamp}.${rawBody}`).digest('hex')
  const a = Buffer.from(parts.v1)
  const b = Buffer.from(expected)
  return a.length === b.length && timingSafeEqual(a, b)
}
```

verify.pyCopiar

```
import hashlib, hmac, time

def verify_singlefax_signature(payload: bytes, header: str, secret: str, tolerance: int = 300) -> bool:
    parts = dict(p.split("=", 1) for p in header.split(","))
    timestamp = int(parts["t"])
    if abs(int(time.time()) - timestamp) > tolerance:
        return False
    expected = hmac.new(
        secret.encode(),
        f"{timestamp}.".encode() + payload,
        hashlib.sha256,
    ).hexdigest()
    return hmac.compare_digest(expected, parts["v1"])
```

## Limitaciones

- Guarda las claves API en el servidor. No incluyas `sf_live_` en una web.
- No envíes PHI. Las entidades sujetas a HIPAA usan HIPAA Secure en la web con BAA electrónico.
- Destinos E.164 válidos. PDF, Word, Excel, PowerPoint, RTF, texto e imágenes; consulta MIME en OpenAPI. No conviertas antes a PDF: lo hacemos antes de enviar.
- MCP de chat y Stripe MPP: [/agents](https://singlefax.com/es/agentes-ia), [mpp.md](https://singlefax.com/mpp.md) y [MPP o pago inmediato](https://singlefax.com/blog/stripe-machine-payments-protocol).

## Preguntas frecuentes

¿CLI, REST o MCP?

¿Necesito crédito antes de enviar?

¿Puedo usar claves sf\_test\_?

¿Hay un SDK oficial?

¿Es compatible con HIPAA?

## Documentación legible por máquinas

Markdown sencillo y OpenAPI para rastreadores y agentes de programación. Los mismos datos que esta página.

[Guía de autenticación](https://singlefax.com/es/autenticacion) [Referencia OpenAPI](https://singlefax.com/es/openapi) [developers.md](https://singlefax.com/developers.md) [openapi.json](https://singlefax.com/openapi.json) [auth.md](https://singlefax.com/auth.md) [llms.txt](https://singlefax.com/llms.txt) [MCP y agentes](https://singlefax.com/es/agentes-ia) [MPP o pago inmediato](https://singlefax.com/blog/stripe-machine-payments-protocol) [versioning.md](https://singlefax.com/versioning.md)

[singlefax](https://singlefax.com/es)

Enviar una vez. Recibe cuando lo necesites.

[![Descárgalo en Google Play](https://singlefax.com/images/google-play-badge.png)](https://play.google.com/store/apps/details?id=com.monocube.singlefax) [Añadir a Chrome](https://chromewebstore.google.com/detail/singlefax-fax-a-document/ojpmpilgkmjcfebhpkdmmjlkbcifkkej) [SingleFax en LinkedIn](https://www.linkedin.com/company/singlefax/) [SingleFax en Facebook](https://www.facebook.com/singlefax) [SingleFax en Instagram](https://www.instagram.com/singlefax.app) [SingleFax en Threads](https://www.threads.com/@singlefax.app) [SingleFax en YouTube](https://www.youtube.com/@singlefax) [SingleFax en GitHub](https://github.com/SingleFax)

## Servicios de fax

- [Enviar un fax](https://singlefax.com/es/enviar-fax?type=send)
- [Recibir faxes](https://singlefax.com/es/enviar-fax?type=receive)
- [Número gratuito de 24 horas](https://singlefax.com/es/numero-fax-gratis)
- [Número de por vida](https://singlefax.com/es/numero-fax-de-por-vida)
- [Portabilidad del número](https://singlefax.com/es/portabilidad-numero-fax)
- [Fax de prueba](https://singlefax.com/es/numero-de-fax-de-prueba)
- [Planes de empresa](https://singlefax.com/es/para-empresas)
- [HIPAA Secure](https://singlefax.com/es/fax-hipaa)
- [Fax por internet](https://singlefax.com/es/fax-por-internet)
- [Enviar fax por correo electrónico](https://singlefax.com/es/enviar-fax-por-correo-electronico)
- [De WhatsApp a fax](https://singlefax.com/es/enviar-fax-por-whatsapp)

## Presentaciones del IRS

- [Todas las presentaciones del IRS](https://singlefax.com/es/tramites-irs)
- [EIN · Formulario SS-4](https://singlefax.com/es/obtener-ein)
- [Formulario 5472](https://singlefax.com/es/presentar-formulario-5472)
- [Formulario 7004](https://singlefax.com/es/presentar-formulario-7004)
- [Formulario 2553](https://singlefax.com/es/presentar-formulario-2553)
- [Formulario 2848](https://singlefax.com/es/presentar-formulario-2848)
- [Formulario 4506-T](https://singlefax.com/es/presentar-formulario-4506-t)
- [Formulario 8821](https://singlefax.com/es/presentar-formulario-8821)
- [Formulario 8802](https://singlefax.com/es/presentar-formulario-8802)
- [Formulario 8655](https://singlefax.com/es/presentar-formulario-8655)
- [Formulario 3911](https://singlefax.com/es/presentar-formulario-3911)
- [Formulario 8233](https://singlefax.com/es/presentar-formulario-8233)
- [NY POA-1](https://singlefax.com/es/presentar-formulario-ny-poa-1)

## Herramientas y recursos

- [Herramientas de fax gratuitas](https://singlefax.com/es/herramientas-fax-gratis)
- [Preparar un PDF para fax](https://singlefax.com/es/preparar-fax)
- [Página de prueba imprimible](https://singlefax.com/es/pagina-de-prueba-fax)
- [Portadas](https://singlefax.com/es/portada-de-fax)
- [Aplicación móvil](https://singlefax.com/es/aplicacion-movil)
- [Extensión de Chrome](https://singlefax.com/es/extension-chrome)
- [Desarrolladores](https://singlefax.com/es/desarrolladores)
- [Fax para agentes de IA](https://singlefax.com/es/agentes-ia)
- [Versionado](https://singlefax.com/es/versionado)
- [Directorio de fax del Congreso](https://singlefax.com/es/fax/congreso)
- [Directorio de faxes del Senado](https://singlefax.com/es/fax/senado)
- [Directorio de fax de gobernadores](https://singlefax.com/es/fax/gobernadores)

## SingleFax

- [Precios](https://singlefax.com/es/precios)
- [Blog](https://singlefax.com/es/blog)
- [Quiénes somos](https://singlefax.com/es/quienes-somos)
- [Contacto](https://singlefax.com/es/contacto)
- [Soporte](https://singlefax.com/es/ayuda)

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```json
{"@context":"https://schema.org","@graph":[{"@id":"https://singlefax.com/es#website","@type":"WebSite","description":"Con SingleFax puedes enviar y recibir faxes puntuales desde el móvil o el ordenador. No necesitas registrarte ni crear una cuenta.","inLanguage":"es","name":"SingleFax – Envía y recibe faxes sin suscripción","url":"https://singlefax.com/es","translationOfWork":{"@id":"https://singlefax.com/#website"}},{"@id":"https://singlefax.com/es/desarrolladores#webpage","description":"Envía faxes desde tu servidor con la API REST y CLI npm de SingleFax. Crédito prepago, claves API, OpenAPI y ejemplos curl, Node, Python, Go y PHP.","name":"Documentación API y CLI: Node, Python, Go y PHP","url":"https://singlefax.com/es/desarrolladores","@type":["WebPage","FAQPage"],"breadcrumb":{"@id":"https://singlefax.com/es/desarrolladores#breadcrumb"},"isPartOf":{"@id":"https://singlefax.com/es#website"},"mainEntity":[{"@id":"https://singlefax.com/es/desarrolladores#/schema/question/1"},{"@id":"https://singlefax.com/es/desarrolladores#/schema/question/2"},{"@id":"https://singlefax.com/es/desarrolladores#/schema/question/3"},{"@id":"https://singlefax.com/es/desarrolladores#/schema/question/4"},{"@id":"https://singlefax.com/es/desarrolladores#/schema/question/5"}],"potentialAction":[{"@type":"ReadAction","target":["https://singlefax.com/es/desarrolladores"]}]},{"@id":"https://singlefax.com/es/desarrolladores#breadcrumb","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","name":"Inicio","item":"https://singlefax.com/es","position":1},{"@type":"ListItem","name":"Desarrolladores","item":"https://singlefax.com/es/desarrolladores","position":2}]},{"@id":"https://singlefax.com/es/desarrolladores#/schema/question/1","@type":"Question","inLanguage":"es","name":"¿CLI, REST o MCP?","acceptedAnswer":{"@type":"Answer","text":"Usa la CLI de npm o REST con clave API y crédito prepago para tu servidor. Envía el Word, Excel, PDF o imagen original; no lo conviertas antes. Los chats Cursor, Claude, Codex y ChatGPT usan MCP en /agents. Los agentes autónomos con Stripe Shared Payment Token o cartera Tempo USDC usan MPP, HTTP 402; consulta /agents y /blog/stripe-machine-payments-protocol."}},{"@id":"https://singlefax.com/es/desarrolladores#/schema/question/2","@type":"Question","inLanguage":"es","name":"¿Necesito crédito antes de enviar?","acceptedAnswer":{"@type":"Answer","text":"Sí, para envíos con clave API. Crea una clave, compra crédito en el panel o con POST /api/v1/credits/checkout y envía. HTTP 402 en /api/v1/faxes significa saldo insuficiente; no es un desafío MPP."}},{"@id":"https://singlefax.com/es/desarrolladores#/schema/question/3","@type":"Question","inLanguage":"es","name":"¿Puedo usar claves sf_test_?","acceptedAnswer":{"@type":"Answer","text":"Las claves de prueba no envían faxes reales. Usa sf_live_. Guarda las claves en el servidor; nunca las incluyas en navegador o aplicación móvil."}},{"@id":"https://singlefax.com/es/desarrolladores#/schema/question/4","@type":"Question","inLanguage":"es","name":"¿Hay un SDK oficial?","acceptedAnswer":{"@type":"Answer","text":"El paquete oficial es la CLI de npm @singlefax/cli. Los ejemplos Python, Go y PHP usan clientes HTTP estándar. No hay SDK separados para Python, Go o Ruby. Usa /openapi.json con herramientas OpenAPI para generar un cliente."}},{"@id":"https://singlefax.com/es/desarrolladores#/schema/question/5","@type":"Question","inLanguage":"es","name":"¿Es compatible con HIPAA?","acceptedAnswer":{"@type":"Answer","text":"No. No envíes PHI por API pública, CLI, MCP o MPP. Las entidades sujetas a HIPAA deben usar HIPAA Secure en la web con BAA electrónico."}}]}
```