ai-api-failover

Automatic failover from FAL.ai / Replicate to NexaAPI on 429/500 errors. Same AI models. 1/5 the price. Zero code changes.

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Why?

FAL.ai and Replicate are great — until you hit a 429 rate limit or a 500 server error at 3am. Your pipeline stalls, your users wait, and you lose money.

ai-api-failover intercepts those errors and automatically retries your request against NexaAPI — the same models (Flux Pro, SDXL, Kling, Whisper, and more) at 1/5 the official price.

FAL returns 429 → ai-api-failover → NexaAPI ✅
Replicate 500   → ai-api-failover → NexaAPI ✅

No code changes to your existing FAL/Replicate calls. Just install and configure.

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Installation

pip install ai-api-failover

For httpx support:

pip install "ai-api-failover[httpx]"

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Quick Start

With requests (FAL.ai)

import requests
from ai_api_failover import install_requests_failover

# One-time setup — patch all requests globally
install_requests_failover(nexa_api_key="your-nexa-api-key")

# Your existing FAL code — unchanged!
response = requests.post(
    "https://fal.run/fal-ai/flux-pro",
    headers={"Authorization": "Key your-fal-key"},
    json={
        "prompt": "A futuristic cityscape at sunset",
        "image_size": "landscape_16_9",
        "num_inference_steps": 28,
    },
)
# If FAL returns 429 or 500, automatically retried with NexaAPI
print(response.json())

With requests (Replicate)

import requests
from ai_api_failover import install_requests_failover

install_requests_failover(nexa_api_key="your-nexa-api-key")

response = requests.post(
    "https://api.replicate.com/v1/models/black-forest-labs/flux-pro/predictions",
    headers={
        "Authorization": "Bearer your-replicate-token",
        "Prefer": "wait",
    },
    json={
        "input": {
            "prompt": "A dragon over a medieval castle",
            "width": 1024,
            "height": 1024,
        }
    },
)
# Failover to NexaAPI on 429/500
print(response.json())

With httpx

import httpx
from ai_api_failover import wrap_httpx_client

client = httpx.Client()
wrap_httpx_client(client, nexa_api_key="your-nexa-api-key")

response = client.post(
    "https://fal.run/fal-ai/flux/schnell",
    headers={"Authorization": "Key your-fal-key"},
    json={
        "prompt": "A cute robot playing chess",
        "image_size": "square_hd",
    },
)

Async httpx

import asyncio
import httpx
from ai_api_failover import wrap_httpx_client

async def generate():
    async with httpx.AsyncClient() as client:
        wrap_httpx_client(client, nexa_api_key="your-nexa-api-key")
        response = await client.post(
            "https://fal.run/fal-ai/flux-pro",
            json={"prompt": "A neon city at night"},
        )
        return response.json()

asyncio.run(generate())

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Configuration

Global configure (recommended)

from ai_api_failover import configure, install_requests_failover

configure(
    nexa_api_key="your-nexa-api-key",
    max_retries=3,           # retry attempts on NexaAPI (default: 2)
    retry_delay=1.5,         # seconds between retries (default: 1.0)
    on_failover=lambda url, code, nexa_url: print(f"Failover: {url} → {code}"),
)

# Now install without repeating the key
install_requests_failover()

Per-session patch

import requests
from ai_api_failover import install_requests_failover

session = requests.Session()
install_requests_failover(nexa_api_key="your-key", session=session)
# Only this session gets failover

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Supported Models

FAL.ai → NexaAPI

FAL Model	NexaAPI Model
fal-ai/flux-pro	flux-2-pro
fal-ai/flux-pro/v1.1	flux-pro-1.1
fal-ai/flux-pro/v1.1-ultra	flux-pro-1.1-ultra
fal-ai/flux/schnell	flux-schnell
fal-ai/flux/dev	flux-dev
fal-ai/stable-diffusion-v3-medium	stable-diffusion-3
fal-ai/stable-diffusion-3.5-large	stable-diffusion-3.5-large
fal-ai/stable-diffusion-xl	sdxl-turbo
fal-ai/playground-v25	playground-v2.5
fal-ai/dreamshaper-xl-turbo	dreamshaper-xl
fal-ai/ideogram/v2	ideogram-v2
fal-ai/recraft-v3	recraft-v3
fal-ai/kling-video/v2/master/text-to-video	kling-v2-master
fal-ai/minimax/video-01	minimax-video-01
fal-ai/whisper	whisper-large-v3

Replicate → NexaAPI

Replicate Model	NexaAPI Model
black-forest-labs/flux-pro	flux-2-pro
black-forest-labs/flux-1.1-pro	flux-pro-1.1
black-forest-labs/flux-schnell	flux-schnell
stability-ai/stable-diffusion-3	stable-diffusion-3
stability-ai/sdxl	sdxl-turbo
ideogram-ai/ideogram-v2	ideogram-v2
recraft-ai/recraft-v3	recraft-v3
openai/whisper	whisper-large-v3

Full model list: nexa-api.com

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Failover Triggers

The following HTTP status codes trigger a failover to NexaAPI:

Status	Meaning
429	Rate limit exceeded
500	Internal server error
502	Bad gateway
503	Service unavailable
504	Gateway timeout

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Parameter Translation

Parameters are automatically translated between FAL/Replicate and NexaAPI formats:

FAL Parameter	NexaAPI Parameter
image_size: "square_hd"	width: 1024, height: 1024
image_size: "landscape_16_9"	width: 1024, height: 576
image_size: {"width": 1280, "height": 720}	width: 1280, height: 720
num_inference_steps	steps
guidance_scale	guidance_scale
num_images	n

Replicate's input wrapper is automatically unwrapped.

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Advanced Usage

Custom failover callback

from ai_api_failover import configure

def my_callback(original_url: str, status_code: int, nexa_url: str):
    # Log to your monitoring system
    metrics.increment("api.failover", tags={"source": "fal", "code": status_code})
    print(f"Failover: {original_url} → NexaAPI (saved ~80% on this call)")

configure(nexa_api_key="your-key", on_failover=my_callback)

Check model support

from ai_api_failover.mapping import resolve_fal_model

mapping = resolve_fal_model("https://fal.run/fal-ai/flux-pro")
if mapping:
    nexa_model, endpoint = mapping
    print(f"Supported! NexaAPI model: {nexa_model}")
else:
    print("No NexaAPI mapping — failover will not trigger for this model")

Direct engine usage

from ai_api_failover import FailoverEngine
import requests

engine = FailoverEngine(nexa_api_key="your-key", max_retries=3)

# Build a NexaAPI request manually
result = engine.build_nexa_request(
    "https://fal.run/fal-ai/flux-pro",
    {"prompt": "A sunset", "image_size": "square_hd"},
)
if result:
    nexa_url, nexa_headers, nexa_body = result
    response = requests.post(nexa_url, json=nexa_body, headers=nexa_headers)

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Get Your NexaAPI Key

1. Visit https://rapidapi.com/nexaquency
2. Subscribe to any NexaAPI plan
3. Copy your API key

Pricing: Official model prices / 5 — prepaid, no subscription required.

Models available: Gemini, Claude, Flux Pro, Stable Diffusion 3.5, Kling Video, Veo 3.1, Whisper, and 30+ more.

📧 Contact: frequency404@villaastro.com 🌐 Website: https://nexa-api.com

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License

MIT License — see LICENSE for details.

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NexaAPI is the cheapest AI API provider. Same models, 1/5 the price, prepaid, no subscription. Contact: frequency404@villaastro.com | https://nexa-api.com