DeepSeek V4.1 Flash Is Now Available on APIMaster.ai

What changed with the official launch?

V4.1 Flash has moved from a temporary preview to an officially released model. For APIMaster developers, the practical change is straightforward: select DeepSeek V4.1 Flash in the marketplace and send requests using deepseek-flash.

Item	September 10 launch update
Model	DeepSeek V4.1 Flash
APIMaster API model ID	deepseek-flash
APIMaster availability	Live; check the marketplace for current routes
Official new-price start	September 10, 2026, 04:00 UTC
V4 Pro service after September 14	API service continues; billing remains unchanged
V4 Pro routing	It will not be routed to V4.1 Flash under the revised notice

APIMaster marketplace snapshot from September 10, 2026. Displayed route prices are a snapshot; use the live marketplace and your account's billing information for current charges.

V4.1 Flash versus V4 Pro: what DeepSeek reports

According to DeepSeek's notice, internal and external testing found that V4.1 Flash surpasses V4 Pro in performance, cost, speed and total completion time. That is DeepSeek's reported conclusion. The notice does not provide benchmark scores or a reproducible test protocol, and this article does not claim an independent APIMaster benchmark.

For developers building coding assistants, document workflows or conversational applications, this makes V4.1 Flash a candidate to evaluate before the Pro transition. Compare representative tasks using answer quality, first-token latency, total completion time and cost per successful task. DeepSeek asks users to report any issues found when comparing V4 Pro with V4.1 Flash.

DeepSeek V4.1 Flash API pricing from September 10

The following is DeepSeek's official pricing in Chinese yuan (CNY/RMB) per 1 million tokens, effective September 10, 2026 at 04:00 UTC. These are upstream rates, not a promise of the same APIMaster route price or a USD conversion.

Billing item, per 1M tokens	Off-peak price (CNY)	Peak price (CNY)
Input: cache hit	0.02	0.04
Input: cache miss	1	2
Output	4	8

Peak hours are Monday through Friday, 01:00-04:00 and 06:00-10:00 UTC. All other hours are off-peak. That includes the weekday lunch interval, evenings and weekends.

Cost example: 1 million uncached input tokens plus 1 million output tokens costs CNY 5 off-peak or CNY 10 at peak under this official table, assuming all usage falls in the same pricing period. Off-peak rates are 50% lower than peak rates for each billing item.

For a mixed workload, calculate cached input, uncached input and output separately. Non-urgent batch jobs may benefit from off-peak scheduling; cache-hit pricing applies to usage actually recorded as cached input.

On APIMaster, check the DeepSeek V4.1 Flash marketplace listing for the current route and displayed currency. Route multipliers and time-based pricing affect the displayed amount, so the official CNY table should not be treated as an APIMaster invoice estimate.

What happens to V4 Pro after September 14?

DeepSeek's notice sets out two stages:

1. Original announcement: DeepSeek initially announced that V4 Pro would be retired and routed to V4.1 Flash at the transition date.
2. Later customer notice: V4 Pro API service continues after September 14, 2026, billing remains unchanged, and V4 Pro will not be routed to V4.1 Flash under the revised plan.

This is the upstream transition announced by DeepSeek. For APIMaster integrations, explicitly selecting deepseek-flash now gives you a clear model target for evaluation; check your chosen route before relying on any legacy Pro alias. A routing transition also means the underlying model can change even when an application's configured model name stays the same.

Before migrating a production workflow, run a small comparison on your own prompts, check response formatting and any tool calls you depend on, and inspect token usage in the console. Keep the model ID configurable so a future migration does not require rewriting your application.

How to use deepseek-flash on APIMaster.ai

APIMaster provides a shared console and an OpenAI-compatible API for supported models. Existing applications can use their APIMaster API key and base URL, then select deepseek-flash as the model.

1. Create an APIMaster account, or sign in to your existing account.
2. Open DeepSeek V4.1 Flash in the marketplace and review the available route and current pricing.
3. Visit the console, add balance as needed and create an API key with access to the model.
4. Set APIMASTER_API_KEY in your local environment and use the following request.

curl "https://apimaster.ai/v1/chat/completions" \
  -H "Authorization: Bearer $APIMASTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "deepseek-flash",
    "messages": [
      {"role": "user", "content": "Write a Python function that removes duplicates from a list while preserving order."}
    ]
  }'

The model ID in this request is deepseek-flash. Replace the temporary preview ID in older examples when moving to the APIMaster launch model.

For more setup details, read the DeepSeek API guide and API key guide. After your first request, review the response and usage in the console before increasing traffic.

Source and billing notice

The release date, official CNY table, peak-hour schedule, V4 Pro transition and performance statement above come from DeepSeek's September 10, 2026 API customer notification. APIMaster availability and the integration ID are supported by our current marketplace listing.

DeepSeek's notice also states that continuing to use its service after the billing adjustment signifies agreement to the new billing method; users who disagree may stop using the service and apply to DeepSeek for a refund. This describes DeepSeek's notice to its own API customers. APIMaster account billing and refund requests follow APIMaster's applicable terms and support process.

FAQ

Is DeepSeek V4.1 Flash available on APIMaster.ai?

Yes. DeepSeek V4.1 Flash is available on APIMaster.ai as deepseek-flash. Check the marketplace for current routes and prices, then use your APIMaster API key to send requests.

What is the API model ID for DeepSeek V4.1 Flash?

Use deepseek-flash with the APIMaster API. The earlier temporary preview identifier is not the model ID used in this launch guide.

What are the official V4.1 Flash API prices?

From September 10, 2026 at 04:00 UTC, official prices per million tokens are CNY 0.02 cached input, CNY 1 uncached input and CNY 4 output off-peak; peak prices are CNY 0.04, CNY 2 and CNY 8 respectively. Check APIMaster's live route prices separately.

When do peak prices apply?

Peak hours are Monday through Friday, 01:00-04:00 and 06:00-10:00 UTC. All remaining hours, including weekends, are off-peak.

Can I still use DeepSeek V4 Pro after September 14, 2026?

Yes. DeepSeek's later customer notice says V4 Pro API service continues after September 14, 2026, billing remains unchanged, and V4 Pro will not be routed to V4.1 Flash under the revised plan.

Does V4.1 Flash outperform V4 Pro?

DeepSeek reports that internal and external tests found V4.1 Flash ahead in performance, cost, speed and total completion time. This article does not present independent APIMaster benchmark results; compare the models on your own workload before migrating.

Start building with DeepSeek V4.1 Flash

DeepSeek V4.1 Flash is ready to use on APIMaster.ai. Whether you are trying DeepSeek for the first time or preparing a V4 Pro migration, start with a representative task, check the result and usage, and expand from there.

Register on APIMaster and start using DeepSeek V4.1 Flash. Already have an account? View deepseek-flash and current pricing, then make your first request from the application you already use.