DeepSeek V4 Flash 0731 offers an exceptionally attractive price-to-speed ratio

DeepSeek has released DeepSeek V4 Flash 0731, the official version of its V4 Flash model. This revision replaces the preview and significantly improves the model's agentic capabilities without giving up what already made it compelling: fast execution at a very low cost.

Read the official DeepSeek V4 Flash 0731 announcement for the release details and published benchmarks.

For developers, it is arguably one of the most attractive models available when looking for a strong balance of price, speed, and quality.

For .NET developers: iolys natively supports DeepSeek inside Visual Studio. You can use V4 Flash 0731 directly with a C# or .NET solution without switching editors or installing an additional connector.

Built for coding agents

DeepSeek says it retained the architecture and size of V4 Flash while reworking its post-training. The objective is clear: improve the model's ability to follow instructions, use tools, and complete development tasks that require multiple steps.

The results published by DeepSeek show substantial progress on Terminal Bench, DeepSWE, Cybergym, and Toolathlon. As always, benchmarks should be treated as indicators rather than guarantees for every project. They nevertheless confirm the strongly agentic direction of this release.

V4 Flash 0731 also retains the important features of the V4 family:

• a context window of up to one million tokens;
• reasoning and non-reasoning modes;
• three reasoning-effort levels: low, high, and max;
• tool calling;
• native support for the OpenAI Responses API format.

The official DeepSeek V4 Flash 0731 model card provides details about the model and its published evaluations.

A huge context window: up to one million tokens

DeepSeek V4 Flash 0731 accepts a context window of up to one million tokens. This changes the scale of the information that can be supplied to the model during a single session.

For a developer, this extended context makes it possible to work with a much larger part of a solution, retain more history, and combine code, specifications, execution logs, and documentation without systematically breaking the request into smaller pieces.

A one-million-token window does not remove the need to select relevant context: sending less information that is more carefully targeted is often more effective. This capacity nevertheless provides considerable headroom for large codebases and long-running agentic tasks.

Pricing that is hard to ignore

As of August 2, 2026, DeepSeek lists V4 Flash at $0.0028 per million cached input tokens, $0.14 per million uncached input tokens, and $0.28 per million output tokens.

These prices are remarkably low, especially for a model offering a one-million-token context window and advanced agentic capabilities. Combined with an architecture designed for fast responses, they make V4 Flash 0731 particularly attractive for frequent tasks: explaining code, preparing a refactoring, generating tests, exploring a codebase, or delegating a series of small changes to an agent.

The best model is not always the one that tops a benchmark. In day-to-day development, response time and cost per interaction matter just as much. V4 Flash 0731 stands out precisely because of this balance.

API pricing may change, so consult the official DeepSeek models and pricing page before estimating the cost of intensive usage.

Fund a DeepSeek account or use OpenRouter

There are two ways to use V4 Flash 0731 in iolys.

The most direct option is the official DeepSeek API. The DeepSeek Platform lets you create or manage an account, add credit, and generate the API key to enter in iolys. Usage and billing then remain directly associated with your DeepSeek account.

You can also access the model through a multi-model provider such as OpenRouter. In that case, fund your OpenRouter account, configure your OpenRouter key in iolys, and select deepseek/deepseek-v4-flash-0731. OpenRouter may offer several infrastructures for serving the same model, so pricing and availability depend on the selected route.

Both direct DeepSeek access and OpenRouter are natively supported by iolys. The main choice is where you want to manage your credits, keys, and billing.

Native DeepSeek support for .NET developers in iolys

iolys natively supports DeepSeek V4 Flash 0731 for C# and .NET developers. There is no need to install an additional connector or leave Visual Studio.

After configuring your DeepSeek credentials in iolys, you can select V4 Flash for your session and use it directly with your active C# or .NET solution. The agent works within the context of the open project: it can help explore the code, explain an implementation, prepare a refactoring, or generate tests while you remain inside Visual Studio.

The model joins the other providers available in the same workspace, with the usual visibility into the session, tools, and requested permissions.

You can therefore choose V4 Flash for tasks where responsiveness and cost control are the priorities, then switch models whenever the work calls for a different balance.

Explore the DeepSeek integration or use OpenRouter with iolys

Sources: official July 31, 2026 announcement and DeepSeek V4 Flash 0731 model card.