flux-2-flex-text-to-image API
Use flux-2-flex-text-to-image from the Flux 2 family via RunAPI. Per-call pricing, no subscription, and failed generations are never charged.
curl -X POST https://runapi.ai/api/v1/flux_2/text_to_image \
-H "Authorization: Bearer $RUNAPI_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "flux-2-flex-text-to-image",
"prompt": "Generate a photorealistic studio portrait of an astronaut holding a cat, dramatic rim lighting, 8K detail."
}'import { Flux2Client } from "@runapi.ai/flux-2";
const client = new Flux2Client();
const result = await client.textToImage.run({
model: "flux-2-flex-text-to-image",
prompt: "Generate a photorealistic studio portrait of an astronaut holding a cat, dramatic rim lighting, 8K detail.",
});<?php
require __DIR__ . "/vendor/autoload.php";
use RunApi\Flux2\Flux2Client;
$client = new Flux2Client();
$result = $client->textToImage->run([
'model' => 'flux-2-flex-text-to-image',
'prompt' => 'Generate a photorealistic studio portrait of an astronaut holding a cat, dramatic rim lighting, 8K detail.',
]);require "runapi/flux_2"
client = RunApi::Flux2::Client.new
result = client.text_to_image.run(
model: "flux-2-flex-text-to-image",
prompt: "Generate a photorealistic studio portrait of an astronaut holding a cat, dramatic rim lighting, 8K detail."
)npx skills add runapi-ai/flux-2 -g# Claude Code
claude mcp add runapi -s user -- npx -y @runapi.ai/mcp
# Codex
codex plugin install runapi-mcp@agents
# Cursor / Windsurf / VS Code
npx @runapi.ai/mcp init cursorflux-2-flex-text-to-image targets the sweet spot of quality and cost within the Flux 2 family. It shares the same API key, request shape, and async task lifecycle as every other RunAPI model — switch to this variant by changing one model ID parameter. Install the Flux 2 skill to load docs, typed schemas, pricing notes, and setup steps into your coding workspace. Billing is metered per completed request in USD with no subscription or minimum spend, and failed generations are never charged.
- Pay-per-call pricing in USD with no subscription
- Failed generations are never charged
- Streaming when supported by the model
- Schema-validated parameters and tool calls
- Switch variant by changing one model ID parameter
- Unified billing across all models and providers
Pricing
Technical details
| Model ID | flux-2-flex-text-to-image |
| Provider | Black Forest Labs |
| Modality | image |
| Task type | asynchronous |
| Billing unit | call |
| API endpoint | /api/v1/flux_2/text_to_image |
| Commercial license | Yes — included via API |
| Catalog status | Operational |
Model skill — flux-2-flex-text-to-image
Install the skill once, then use the variant ID from this page while building.
# Install the model skill for app development workflows
npx skills add runapi-ai/flux-2 -gInstall the Flux 2 skill for this app: 1. Add runapi-ai/flux-2 with the skills installer. 2. Load SKILL.md in this workspace. 3. Use its docs, schemas, pricing notes, and setup steps when adding model features. 4. Confirm the install path when done.
Use flux-2-flex-text-to-image with a model skill
Install
Install the model skill for the %{model} line. The skill loads docs, typed schemas, pricing notes, and setup steps into your coding workspace so your agent has the right context.
Configure
Set the model field to the full model ID shown on this page and configure your RunAPI API key as an environment variable. The same key works across all models and providers.
Call
Use the skill instructions while adding prompt, input, and callback handling to your application. RunAPI routes the request to the provider, manages the async lifecycle, and returns structured JSON.
Receive
Read the task response by polling the task ID, streaming when supported, or handling the webhook callback at your configured URL. Generated outputs are stored and retrievable by task ID.
What's different about flux-2-flex-text-to-image
Adjustable steps + guidance; up to 10 ref images; best typography
Flex control + reference image input
Adjustable steps + guidance; up to 10 ref images; best typography
Pro quality with input image as style/content seed
Adjustable steps + guidance; up to 10 ref images; best typography
Zero-config flagship; automatic prompt enhancement
Best for
Product photography
Auto-generate lifestyle product photos for e-commerce catalogs that lack studio photography.
Game & concept art
Rapidly concept environments and characters before committing to final art.
Editorial illustration
Generate unique cover art and illustrations for blog posts and articles at scale.
Frequently asked questions about flux-2-flex-text-to-image
Is the model ID stable across versions?
Yes. RunAPI keeps the model ID stable and handles compatible version refreshes without changing your request shape. You do not need to update your code when the provider releases a new compatible version.
What's the rate limit on this variant?
Per-key rate limits scale with your usage tier. The pricing page shows current limits. If you need higher throughput, contact support to discuss tier upgrades.
Can I switch variants later?
Yes. Variant is a parameter in the request. Switch by changing the model ID — no code changes, no re-authentication, no separate billing setup. All variants share the same API key and request shape.
Does it stream?
Where streaming is available, RunAPI streams end-to-end. LLM models support token-level streaming. Media models use async task polling or webhook callbacks for result delivery.
Where do I report quality issues?
Open an issue on the public GitHub repo or email support at [email protected]. Include the task ID and model ID so the team can investigate the specific generation.
Do I need a separate provider account?
No. Your RunAPI API key is enough to access this variant and every other model in the catalog. You do not need accounts with the underlying provider.
Other variants of Flux 2
Alternatives from other models
Flux Kontext
GPT Image
GPT Image 2