title: OpenAI o1 and new tools for developers
contenttype: article
publication: OpenAI
published: 2026-02-25T00:00:00
sourceurl: https://openai.com/index/o1-and-new-tools-for-developers

word_count: 1591

OpenAI o1 and new tools for developers

Introducing OpenAI o1, Realtime API improvements, a new fine-tuning method and more for developers.

Today we’re introducing more capable models, new tools for customization, and upgrades that improve performance, flexibility, and cost-efficiency for developers building with AI. This includes:

, with support for function calling, developer messages, Structured Outputs, and vision capabilities.(opens in a new window)OpenAI o1 in the API, including simple WebRTC integration, a 60% price reduction for GPT‑4o audio, and support for GPT‑4o mini at one-tenth of previous audio rates.(opens in a new window)Realtime API updates, a new model customization technique that makes it easier to tailor models based on user and developer preferences.(opens in a new window)Preference Fine-Tuningavailable in beta.(opens in a new window)New Go and Java SDKs

OpenAI o1, our reasoning model designed to handle complex multi-step tasks with advanced accuracy, is rolling out to developers on

in the API. o1 is the successor to OpenAI

usage tier 5(opens in a new window), which developers have already used to build agentic applications to streamline customer support, optimize supply chain decisions, and forecast complex financial trends.

o1‑previewo1 is production-ready with key features to enable real-world use cases, including:

: Seamlessly connect o1 to external data and APIs.(opens in a new window)Function calling: Generate responses that reliably adhere to your custom JSON Schema.(opens in a new window)Structured OutputsDeveloper messages: Specify instructions or context for the model to follow, such as defining tone, style and other behavioral guidance.Vision capabilities: Reason over images to unlock many more applications in science, manufacturing, or coding, where visual inputs matter.Lower latency: o1 uses on average 60% fewer reasoning tokens than o1‑preview for a given request.- A new **reasoning_effort** API parameter allows you to control how long the model thinks before answering.

The snapshot of o1 we’re shipping today o1‑2024‑12‑17

is a new post-trained version of the model we released in ChatGPT two weeks ago. It improves on areas of model behavior based on feedback, while maintaining the frontier capabilities we evaluated in our o1 System Card. We’re also updating o1 in ChatGPT to this version soon. The evaluations we’re sharing below reflect the performance of this new snapshot, ensuring developers have up-to-date benchmarks for this version.

o1‑2024‑12‑17

sets new state-of-the-art results on several benchmarks, improving cost-efficiency and performance.

Model Evaluation Accuracy Across Different Metrics

Additionally, we have observed that o1‑2024‑12‑17

significantly outperforms gpt-4o in our function calling and Structured Outputs testing.

We are rolling out access incrementally while working to expand access to additional usage tiers and ramping up rate limits. To get started, check out the API documentation(opens in a new window).

The Realtime API(opens in a new window) enables developers to create low-latency, natural conversational experiences. It’s ideal for voice assistants, live translation tools, virtual tutors, interactive customer support systems, or even your own virtual

. Today we’re releasing changes to address some of the most common requests from developers: a direct WebRTC integration, reduced pricing, and more control over responses.

Santa(opens in a new window)We’re introducing WebRTC(opens in a new window) support for the Realtime API. WebRTC is an open standard that makes it easier to build and scale real-time voice products across platforms—whether for browser-based apps, mobile clients, IoT devices, or direct server-to-server setups.

Our WebRTC integration is designed to enable smooth and responsive interactions in real-world conditions, even with variable network quality. It handles audio encoding, streaming, noise suppression, and congestion control.

With WebRTC, you can now add Realtime capabilities with just a handful of lines of Javascript:

Learn more about our WebRTC integration in the API documentation(opens in a new window).

We’re releasing gpt-4o-realtime-preview-2024-12-17

as part of the Realtime API beta with improved voice quality, more reliable input (especially for dictated numbers), and reduced costs. Due to our efficiency improvements, we’re dropping the audio token price by 60% to $40/1M input tokens and $80/1M output tokens. Cached audio input costs are reduced by 87.5% to $2.50/1M input tokens.

We’re also bringing GPT‑4o mini to the Realtime API beta as gpt-4o-mini-realtime-preview-2024-12-17

. GPT‑4o mini is our most cost-efficient small model and brings the same rich voice experiences to the Realtime API as GPT‑4o. GPT‑4o mini audio price is $10/1M input tokens and $20/1M output tokens. Text tokens are priced at $0.60/1M input tokens and $2.40/1M output tokens. Cached audio and text both cost $0.30/1M tokens.

These snapshots are available in the Realtime API(opens in a new window) and also in the

as

Chat Completions API(opens in a new window)gpt-4o-audio-preview-2024-12-17

and gpt-4o-mini-audio-preview-2024-12-17

.We’re shipping the following features to the Realtime API to make it easier to deliver exceptional voice-driven experiences:

to enable background tasks such as content moderation or classification to run without interrupting the user’s voice interaction.(opens in a new window)Concurrent out-of-band responsesto specify which conversation items to include as model input. For example, run a moderation check on just the user’s last utterance or re-use a past response without permanently altering the session state.(opens in a new window)Custom input context(opens in a new window)Controlled response timingto use server-side Voice Activity Detection (VAD) without automatically triggering a response. For instance, gather necessary data such as account details and add it to the model’s context before manually initiating a voice reply, offering more control over timing and accuracy.from 15 to 30 min.(opens in a new window)Increased maximum session length

The fine-tuning API now supports Preference Fine-Tuning(opens in a new window) to make it easy to customize models based on user and developer preferences. This method uses

to compare pairs of model responses, teaching the model to distinguish between preferred and non-preferred outputs. By learning from pairwise comparisons rather than fixed targets, Preference Fine-Tuning is especially effective for subjective tasks where tone, style, and creativity matter.

Direct Preference Optimization (DPO)(opens in a new window)There are some key differences between Preference Fine-Tuning and Supervised Fine-Tuning, as shown below.

|
| |
| Encourage the model to generate correct outputs by replicating labeled outputs | Optimize the model to favor desired behavior by reinforcing preferred responses and reducing the likelihood of unpreferred ones |
| Exact input and output pairs | Pairs of preferred and non-preferred model output, via human annotation, A/B testing, or synthetic data generation |
| Tasks where an ideal output is easy to prepare, such as custom code format, and strict correctness is needed | Effective for tasks where “better” responses are subjective, such as creative writing or summarization. |

We started testing Preference Fine-Tuning with trusted partners who have seen promising results so far. For example, Rogo AI(opens in a new window) is building an AI assistant for financial analysts that breaks down complex queries into sub-queries. Using their expert-built benchmark, Rogo-Golden, they found that while Supervised Fine-Tuning faced challenges with out-of-distribution query expansion—such as missing metrics like ARR for queries like “how fast is company X growing”—Preference Fine-Tuning resolved these issues, improving performance from 75% accuracy in the base model to over 80%.

Preference Fine-Tuning will roll out today for gpt-4o-2024-08-06

and will be available for gpt-4o-mini-2024-07-18

soon. It will be available at the same price per trained token as Supervised Fine-Tuning, with support for our newest models coming early next year. For more information, visit our fine-tuning guide(opens in a new window) in the API documentation.

Finally, we’re introducing two new official SDKs for Go(opens in a new window) and

in beta, in addition to

Java(opens in a new window). Our goal is for OpenAI APIs to be easy to use, no matter what programming language you choose.

our existing official Python, Node.js and .NET libraries(opens in a new window)Go is a statically typed language ideal for handling concurrency and building scalable APIs and backend systems. The OpenAI Go SDK makes it easy to interact with OpenAI models in your Go code.

For more information on the Go SDK, check out the README on GitHub(opens in a new window).

Java has been a staple of enterprise software development, favored for its type system and massive ecosystem of open-source libraries. The OpenAI Java SDK provides typed request and response objects, and helpful utilities to manage API requests.

For more information on the Java SDK, check out the README on GitHub(opens in a new window).

We’re excited to see what you’ll build with these updates—whether it’s new voice apps, fine-tuned models, or agentic applications that push the boundaries of what’s possible. Check out the detailed guides for o1(opens in a new window),

,

Realtime API(opens in a new window), and

WebRTC integration(opens in a new window)in our API documentation to dive deeper and start experimenting today.

Preference Fine-Tuning(opens in a new window)Have questions? Connect with our team on the OpenAI Developer Forum(opens in a new window).