---
title: "OpenAI's large language models"
source: "https://systems-analysis.info/eng/OpenAI's_large_language_models"
wiki: "systems-analysis.info/eng"
article: "OpenAI's_large_language_models"
language: "en"
categories:
  - "Category:English"
  - "Category:Large language models"
  - "Category:LLM families"
  - "Category:Machine learning"
  - "Category:OpenAI"
  - "Category:Technology"
revision_id: 277
wiki_created_at: 2026-09-06T22:19:56Z
wiki_modified_at: 2026-09-06T22:19:56Z
downloaded_at: 2026-09-07T22:22:25Z
---

# OpenAI's large language models

**OpenAI's large language models** are a series of large language models (LLMs) developed by the research lab <a href="https://openai.com/" class="external text" rel="nofollow">OpenAI</a>. These models, built on the [Transformer](https://systems-analysis.info/eng/Transformer_architecture "Transformer architecture") architecture, have become a key factor in the development of generative artificial intelligence. Starting with the GPT-1 model, introduced in 2018, each subsequent generation—including GPT-2, GPT-3, GPT-4, and newer multimodal systems like GPT-4o and the O-series family—has demonstrated exponential growth in capabilities, scale, and impact.

## Evolution of GPT Models

### GPT-1 (2018)

The first model in the series, introduced in 2018.

- **Parameters:** 117 million.
- **Architecture:** 12-layer Transformer decoder.
- **Training:** Trained on the **BookCorpus** dataset (~7,000 unpublished books).
- **Key Innovation:** Demonstrated the effectiveness of the two-stage approach (pre-training + fine-tuning), laying the foundation for all subsequent models. It proved that a single model could be adapted to numerous NLP tasks without architectural changes.

### GPT-2 (2019)

A significant scaling-up from GPT-1.

- **Parameters:** 1.5 billion (~10x more than GPT-1).
- **Architecture:** 48-layer Transformer decoder.
- **Training:** Trained on the **WebText** corpus (40 GB of high-quality text filtered from the internet).
- **Key Innovation:** Showcased impressive **zero-shot** learning capabilities, i.e., solving tasks without specific fine-tuning. It could generate long and coherent texts. Its release was accompanied by public debate about the risks of misuse, which led OpenAI to initially release only smaller versions of the model.

### GPT-3 (2020)

The model that brought a breakthrough in the capabilities and public perception of LLMs.

- **Parameters:** 175 billion (~100x more than GPT-2).
- **Architecture:** 96-layer Transformer decoder.
- **Training:** Trained on a mixture of datasets totaling ~570 GB, including Common Crawl, books, and Wikipedia.
- **Key Innovation:** Emergence of strong **few-shot** learning abilities—the model could solve tasks after being given just a few examples in the prompt itself. GPT-3 was the first model OpenAI offered via a commercial API, kicking off a boom in generative AI startups.

### InstructGPT and GPT-3.5 (2022)

A family of models focused on improving controllability and usefulness.

- **Parameters:** Comparable to GPT-3 (~175 billion).
- **Training:** The **RLHF** method was applied on a massive scale for the first time to teach the model to follow instructions better, be more truthful, and less toxic.
- **Key Innovation:** A sharp increase in the model's "alignment" and safety. The **gpt-3.5-turbo** model formed the basis of the first release of **ChatGPT**, which launched on November 30, 2022, and became a global phenomenon.

### GPT-4 (2023)

A new flagship model that marked the transition to multimodality.

- **Parameters:** Not officially disclosed (estimates are ~1.7 trillion, possibly with a Mixture-of-Experts architecture).
- **Architecture:** Multimodal Transformer.
- **Training:** Trained on a vast corpus of text and images.
- **Key Innovation:** **Multimodality**—the ability to accept not only text but also images as input. It demonstrated human-level (and even superhuman) performance on many professional and academic benchmarks (e.g., the bar exam).

### GPT-4 Turbo (2023)

An optimized and more affordable version of GPT-4.

- **Parameters:** Similar to GPT-4.
- **Context Window:** Increased to **128,000 tokens** (~300 pages of text).
- **Training:** Updated knowledge (up to April 2023).
- **Key Innovation:** A significant reduction in API call costs, improved instruction-following, and more recent knowledge, making the power of GPT-4 accessible to a wider range of applications.

### GPT-4o (2024)

The "omni-model," which natively processes multiple modalities.

- **Key Innovation:** Native **multimodal processing** of text, audio, and images in real-time within a single model. This enables very fast and natural responses, comparable to the speed of human conversation. GPT-4o made GPT-4-level capabilities available to free ChatGPT users.

### O-series Family: o1 and o3 (2024-2025)

A new generation of models focused on developing **reasoning** abilities.

- **o1 model** (September 2024): Introduced as a significant step forward in cognitive functions, allowing it to solve more complex problems that require deep analysis and multi-step reasoning.
- **o3 model** (January 2025): A further development of the ideas in o1, with even higher scores on complex logic and math tests (e.g., 96.7% on the 2024 AIME exam).
- **Key Innovation:** A focus not just on text generation but on constructing logical chains (Chain-of-Thought) and solving complex problems, bringing AI closer to more abstract thinking.

## Models

<table class="wikitable sortable" style="width:100%;">
<colgroup>
<col style="width: 14%" />
<col style="width: 14%" />
<col style="width: 14%" />
<col style="width: 14%" />
<col style="width: 14%" />
<col style="width: 14%" />
<col style="width: 14%" />
</colgroup>
<thead>
<tr class="header">
<th>No.</th>
<th>Date</th>
<th>Model</th>
<th>Note</th>
<th>Source</th>
<th>Developer</th>
<th>System Card</th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td>1</td>
<td>2018-06-11</td>
<td>GPT / GPT-1</td>
<td>First GPT-line model; transformer-based language model trained with unsupervised pre-training and supervised fine-tuning.</td>
<td><a href="https://openai.com/index/language-unsupervised/" class="external text" rel="nofollow">OpenAI</a></td>
<td>—</td>
<td>—</td>
</tr>
<tr class="even">
<td>2</td>
<td>2019-02-14</td>
<td>GPT-2</td>
<td>Large unsupervised language model; released gradually because of misuse concerns.</td>
<td><a href="https://openai.com/index/better-language-models/" class="external text" rel="nofollow">OpenAI</a></td>
<td>—</td>
<td>—</td>
</tr>
<tr class="odd">
<td>3</td>
<td>2020-05-28</td>
<td>GPT-3</td>
<td>175B-parameter language model demonstrating strong few-shot learning.</td>
<td><a href="https://openai.com/index/language-models-are-few-shot-learners/" class="external text" rel="nofollow">OpenAI</a></td>
<td>—</td>
<td>—</td>
</tr>
<tr class="even">
<td>4</td>
<td>2022-01-27</td>
<td>InstructGPT</td>
<td>Instruction-following GPT-3-based models trained with human feedback.</td>
<td><a href="https://openai.com/index/instruction-following/" class="external text" rel="nofollow">OpenAI</a></td>
<td>—</td>
<td>—</td>
</tr>
<tr class="odd">
<td>5</td>
<td>2022-11-30</td>
<td>ChatGPT / GPT-3.5</td>
<td>Conversational model related to InstructGPT; launched as a research preview.</td>
<td><a href="https://openai.com/index/chatgpt/" class="external text" rel="nofollow">OpenAI</a></td>
<td>—</td>
<td>—</td>
</tr>
<tr class="even">
<td>6</td>
<td>2023-03-01</td>
<td>GPT-3.5 Turbo</td>
<td>API model family used in ChatGPT; optimized for chat and lower cost.</td>
<td><a href="https://openai.com/index/introducing-chatgpt-and-whisper-apis/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-3.5-turbo" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>—</td>
</tr>
<tr class="odd">
<td>7</td>
<td>2023-03-14</td>
<td>GPT-4</td>
<td>Large multimodal model accepting image and text inputs and producing text outputs.</td>
<td><a href="https://openai.com/index/gpt-4-research/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-4" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://arxiv.org/abs/2303.08774" class="external text" rel="nofollow">arXiv:2303.08774</a><br />
<a href="https://cdn.openai.com/papers/gpt-4-system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>8</td>
<td>2023-11-06</td>
<td>GPT-4 Turbo</td>
<td>More capable and cheaper GPT-4 variant with a 128K context window.</td>
<td><a href="https://openai.com/index/new-models-and-developer-products-announced-at-devday/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-4-turbo" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>—</td>
</tr>
<tr class="odd">
<td>9</td>
<td>2024-05-13</td>
<td>GPT-4o</td>
<td>Omni flagship model for real-time reasoning across audio, vision, and text.</td>
<td><a href="https://openai.com/index/hello-gpt-4o/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-4o" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://arxiv.org/abs/2410.21276" class="external text" rel="nofollow">arXiv:2410.21276</a><br />
<a href="https://cdn.openai.com/gpt-4o-system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>10</td>
<td>2024-07-18</td>
<td>GPT-4o mini</td>
<td>Smaller and cheaper GPT-4o-class model for cost-efficient intelligence.</td>
<td><a href="https://openai.com/index/gpt-4o-mini-advancing-cost-efficient-intelligence/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-4o-mini" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>Covered in GPT-4o System Card:<br />
<a href="https://arxiv.org/abs/2410.21276" class="external text" rel="nofollow">arXiv:2410.21276</a><br />
<a href="https://cdn.openai.com/gpt-4o-system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="odd">
<td>11</td>
<td>2024-09-12</td>
<td>OpenAI o1-preview</td>
<td>First public preview model in the o-series, designed to spend more time reasoning before answering.</td>
<td><a href="https://openai.com/index/introducing-openai-o1-preview/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/o1-preview" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/o1-system-card-20240917.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>12</td>
<td>2024-09-12</td>
<td>OpenAI o1-mini</td>
<td>Separate smaller reasoning model; faster and more cost-efficient, especially for STEM and coding.</td>
<td><a href="https://openai.com/index/openai-o1-mini-advancing-cost-efficient-reasoning/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/o1-mini" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://arxiv.org/abs/2412.16720" class="external text" rel="nofollow">arXiv:2412.16720</a><br />
<a href="https://cdn.openai.com/o1-system-card-20240917.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="odd">
<td>13</td>
<td>2024-12-05</td>
<td>OpenAI o1</td>
<td>Full o1 reasoning model; successor to o1-preview.</td>
<td><a href="https://openai.com/index/o1-and-new-tools-for-developers/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/o1" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://arxiv.org/abs/2412.16720" class="external text" rel="nofollow">arXiv:2412.16720</a><br />
<a href="https://cdn.openai.com/o1-system-card-20241205.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>14</td>
<td>2024-12-05</td>
<td>o1 pro mode / o1-pro</td>
<td>Higher-compute version of o1 for harder problems and more reliable answers.</td>
<td><a href="https://openai.com/index/introducing-chatgpt-pro/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/o1-pro" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>—</td>
</tr>
<tr class="odd">
<td>15</td>
<td>2025-01-31</td>
<td>OpenAI o3-mini</td>
<td>Small, fast, cost-efficient reasoning model with strong STEM, math, and coding performance.</td>
<td><a href="https://openai.com/index/openai-o3-mini/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/o3-mini" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/o3-mini-system-card-feb10.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>16</td>
<td>2025-02-27</td>
<td>GPT-4.5</td>
<td>Research preview GPT model focused on broader pre-training and non-reasoning intelligence.</td>
<td><a href="https://openai.com/index/introducing-gpt-4-5/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-4.5-preview" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/gpt-4-5-system-card-2272025.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="odd">
<td>17</td>
<td>2025-04-14</td>
<td>GPT-4.1</td>
<td>API model with improvements in coding, instruction following, and long-context use.</td>
<td><a href="https://openai.com/index/gpt-4-1/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-4.1" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://openai.com/index/gpt-4-1/" class="external text" rel="nofollow">OpenAI System Card</a></td>
</tr>
<tr class="even">
<td>18</td>
<td>2025-04-14</td>
<td>GPT-4.1 mini</td>
<td>Smaller and faster version of GPT-4.1.</td>
<td><a href="https://openai.com/index/gpt-4-1/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-4.1-mini" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://openai.com/index/gpt-4-1/" class="external text" rel="nofollow">OpenAI System Card</a></td>
</tr>
<tr class="odd">
<td>19</td>
<td>2025-04-14</td>
<td>GPT-4.1 nano</td>
<td>Smallest and lowest-cost version of GPT-4.1.</td>
<td><a href="https://openai.com/index/gpt-4-1/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-4.1-nano" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://openai.com/index/gpt-4-1/" class="external text" rel="nofollow">OpenAI System Card</a></td>
</tr>
<tr class="even">
<td>20</td>
<td>2025-04-16</td>
<td>OpenAI o3</td>
<td>Advanced reasoning model for coding, math, science, and visual reasoning.</td>
<td><a href="https://openai.com/index/introducing-o3-and-o4-mini/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/o3" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/pdf/2221c875-02dc-4789-800b-e7758f3722c1/o3-and-o4-mini-system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="odd">
<td>21</td>
<td>2025-04-16</td>
<td>OpenAI o4-mini</td>
<td>Smaller reasoning model optimized for speed, cost, and strong multimodal reasoning.</td>
<td><a href="https://openai.com/index/introducing-o3-and-o4-mini/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/o4-mini" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/pdf/2221c875-02dc-4789-800b-e7758f3722c1/o3-and-o4-mini-system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>22</td>
<td>2025-06-10</td>
<td>OpenAI o3-pro</td>
<td>Higher-compute version of o3 designed to think longer and provide more reliable answers.</td>
<td><a href="https://openai.com/index/introducing-o3-and-o4-mini/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/o3-pro" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>Covered by o3 System Card:<br />
<a href="https://cdn.openai.com/pdf/2221c875-02dc-4789-800b-e7758f3722c1/o3-and-o4-mini-system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="odd">
<td>23</td>
<td>2025-08-05</td>
<td>gpt-oss-120b</td>
<td>Open-weight reasoning model released under the Apache 2.0 license.</td>
<td><a href="https://openai.com/index/introducing-gpt-oss/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-oss-120b" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>—</td>
</tr>
<tr class="even">
<td>24</td>
<td>2025-08-05</td>
<td>gpt-oss-20b</td>
<td>Smaller open-weight reasoning model released under the Apache 2.0 license.</td>
<td><a href="https://openai.com/index/introducing-gpt-oss/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-oss-20b" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>—</td>
</tr>
<tr class="odd">
<td>25</td>
<td>2025-08-07</td>
<td>GPT-5</td>
<td>Unified flagship model system with fast and thinking capabilities.</td>
<td><a href="https://openai.com/index/introducing-gpt-5/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://arxiv.org/abs/2601.03267" class="external text" rel="nofollow">arXiv:2601.03267</a><br />
<a href="https://cdn.openai.com/gpt-5-system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>26</td>
<td>2025-08-07</td>
<td>GPT-5 mini</td>
<td>Smaller GPT-5 API model balancing capability, cost, and latency.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-for-developers/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5-mini" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>Covered in GPT-5 System Card:<br />
<a href="https://arxiv.org/abs/2601.03267" class="external text" rel="nofollow">arXiv:2601.03267</a><br />
<a href="https://cdn.openai.com/gpt-5-system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="odd">
<td>27</td>
<td>2025-08-07</td>
<td>GPT-5 nano</td>
<td>Smallest GPT-5 API model for lowest-latency and lowest-cost use cases.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-for-developers/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5-nano" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>Covered in GPT-5 System Card:<br />
<a href="https://arxiv.org/abs/2601.03267" class="external text" rel="nofollow">arXiv:2601.03267</a><br />
<a href="https://cdn.openai.com/gpt-5-system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>28</td>
<td>2025-08-07</td>
<td>GPT-5 Pro / GPT-5 Thinking Pro</td>
<td>Extended-reasoning GPT-5 variant for harder tasks.</td>
<td><a href="https://openai.com/index/gpt-5-system-card/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5-pro" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>Covered in GPT-5 System Card:<br />
<a href="https://arxiv.org/abs/2601.03267" class="external text" rel="nofollow">arXiv:2601.03267</a><br />
<a href="https://cdn.openai.com/gpt-5-system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="odd">
<td>29</td>
<td>2025-11-12</td>
<td>GPT-5.1 Instant</td>
<td>More conversational GPT-5.1 chat model with improved instruction following.</td>
<td><a href="https://openai.com/index/gpt-5-1/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.1-chat-latest" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/pdf/4173ec8d-1229-47db-96de-06d87147e07e/5_1_system_card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>30</td>
<td>2025-11-12</td>
<td>GPT-5.1 Thinking</td>
<td>GPT-5.1 reasoning model with more adaptive thinking time.</td>
<td><a href="https://openai.com/index/gpt-5-1/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.1" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/pdf/4173ec8d-1229-47db-96de-06d87147e07e/5_1_system_card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="odd">
<td>31</td>
<td>2025-12-11</td>
<td>GPT-5.2 Instant</td>
<td>Instant variant of GPT-5.2 for ChatGPT and API use.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-2/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.2-chat-latest" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/pdf/3a4153c8-c748-4b71-8e31-aecbde944f8d/oai_5_2_system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>32</td>
<td>2025-12-11</td>
<td>GPT-5.2 Thinking</td>
<td>Reasoning variant of GPT-5.2 with stronger scientific and mathematical performance.</td>
<td><a href="https://openai.com/index/gpt-5-2-for-science-and-math/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.2" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/pdf/3a4153c8-c748-4b71-8e31-aecbde944f8d/oai_5_2_system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="odd">
<td>33</td>
<td>2025-12-11</td>
<td>GPT-5.2 Pro</td>
<td>Pro variant of GPT-5.2 for harder reasoning and professional work.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-2/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.2-pro" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/pdf/3a4153c8-c748-4b71-8e31-aecbde944f8d/oai_5_2_system-card.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="even">
<td>34</td>
<td>2026-02-05</td>
<td>GPT-5.3-Codex</td>
<td>Specialized agentic coding model for Codex-style long-running software tasks.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-3-codex/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.3-codex" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://cdn.openai.com/pdf/23eca107-a9b1-4d2c-b156-7deb4fbc697c/GPT-5-3-Codex-System-Card-02.pdf" class="external text" rel="nofollow">CDN PDF</a></td>
</tr>
<tr class="odd">
<td>35</td>
<td>2026-03-03</td>
<td>GPT-5.3 Instant</td>
<td>Updated everyday ChatGPT model focused on smoother and more useful answers.</td>
<td><a href="https://openai.com/index/gpt-5-3-instant/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.3-chat-latest" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://deploymentsafety.openai.com/gpt-5-3-instant/gpt-5-3-instant.pdf" class="external text" rel="nofollow">DSH PDF</a></td>
</tr>
<tr class="even">
<td>36</td>
<td>2026-03-05</td>
<td>GPT-5.4</td>
<td>General-purpose frontier model with native computer-use capabilities.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-4/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.4" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://deploymentsafety.openai.com/gpt-5-4-thinking/gpt-5-4-thinking.pdf" class="external text" rel="nofollow">DSH PDF</a></td>
</tr>
<tr class="odd">
<td>37</td>
<td>2026-03-05</td>
<td>GPT-5.4 Pro</td>
<td>Pro version of GPT-5.4 for more complex professional and agentic tasks.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-4/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.4-pro" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://deploymentsafety.openai.com/gpt-5-4-thinking/gpt-5-4-thinking.pdf" class="external text" rel="nofollow">DSH PDF</a></td>
</tr>
<tr class="even">
<td>38</td>
<td>2026-03-17</td>
<td>GPT-5.4 mini</td>
<td>Smaller and faster GPT-5.4-class model for coding, tool use, and multimodal reasoning.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-4-mini-and-nano/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.4-mini" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://deploymentsafety.openai.com/gpt-5-4-thinking/appendix-gpt-5.4-mini" class="external text" rel="nofollow">DSH appendix</a></td>
</tr>
<tr class="odd">
<td>39</td>
<td>2026-03-17</td>
<td>GPT-5.4 nano</td>
<td>Smallest GPT-5.4-class model for high-volume and low-cost API workloads.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-4-mini-and-nano/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.4-nano" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td>—</td>
</tr>
<tr class="even">
<td>40</td>
<td>2026-04-23</td>
<td>GPT-5.5</td>
<td>Flagship GPT-5.5 model for professional work, coding, research, and analysis.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-5/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.5" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://deploymentsafety.openai.com/gpt-5-5/gpt-5-5.pdf" class="external text" rel="nofollow">DSH PDF</a></td>
</tr>
<tr class="odd">
<td>41</td>
<td>2026-04-23</td>
<td>GPT-5.5 Pro</td>
<td>Pro version of GPT-5.5 for more demanding reasoning and professional tasks.</td>
<td><a href="https://openai.com/index/introducing-gpt-5-5/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/gpt-5.5-pro" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://deploymentsafety.openai.com/gpt-5-5/gpt-5-5.pdf" class="external text" rel="nofollow">DSH PDF</a></td>
</tr>
<tr class="even">
<td>42</td>
<td>2026-05-05</td>
<td>GPT-5.5 Instant</td>
<td>Updated default ChatGPT model with improved accuracy, clarity, and personalization.</td>
<td><a href="https://openai.com/index/gpt-5-5-instant/" class="external text" rel="nofollow">OpenAI</a></td>
<td><a href="https://developers.openai.com/api/docs/models/chat-latest" class="external text" rel="nofollow">OpenAI API docs</a></td>
<td><a href="https://deploymentsafety.openai.com/gpt-5-5-instant" class="external text" rel="nofollow">DSH</a></td>
</tr>
<tr class="odd">
<td>43</td>
<td>2026-06-26</td>
<td>GPT-5.6 Sol</td>
<td>Limited-preview flagship model in the GPT-5.6 series.</td>
<td><a href="https://openai.com/index/previewing-gpt-5-6-sol/" class="external text" rel="nofollow">OpenAI</a></td>
<td>—</td>
<td><a href="https://deploymentsafety.openai.com/gpt-5-6-preview/gpt-5-6-preview.pdf" class="external text" rel="nofollow">DSH PDF</a></td>
</tr>
<tr class="even">
<td>44</td>
<td>2026-06-26</td>
<td>GPT-5.6 Terra</td>
<td>Limited-preview balanced GPT-5.6 model for everyday work.</td>
<td><a href="https://openai.com/index/previewing-gpt-5-6-sol/" class="external text" rel="nofollow">OpenAI</a></td>
<td>—</td>
<td><a href="https://deploymentsafety.openai.com/gpt-5-6-preview/gpt-5-6-preview.pdf" class="external text" rel="nofollow">DSH PDF</a></td>
</tr>
<tr class="odd">
<td>45</td>
<td>2026-06-26</td>
<td>GPT-5.6 Luna</td>
<td>Limited-preview fast and affordable GPT-5.6 model.</td>
<td><a href="https://openai.com/index/previewing-gpt-5-6-sol/" class="external text" rel="nofollow">OpenAI</a></td>
<td>—</td>
<td><a href="https://deploymentsafety.openai.com/gpt-5-6-preview/gpt-5-6-preview.pdf" class="external text" rel="nofollow">DSH PDF</a></td>
</tr>
</tbody>
</table>

## External links

- <a href="https://openai.com/" class="external text" rel="nofollow">Official OpenAI website</a>
- <a href="https://en.wikipedia.org/wiki/Generative_pre-trained_transformer" class="external text" rel="nofollow">Generative pre-trained transformer — Wikipedia</a>
- <a href="https://en.wikipedia.org/wiki/OpenAI" class="external text" rel="nofollow">OpenAI — Wikipedia</a>
- <a href="https://en.wikipedia.org/wiki/List_of_large_language_models" class="external text" rel="nofollow">List of large language models — Wikipedia</a>

## Literature

- Radford, A. et al. (2018). *Improving Language Understanding by Generative Pre-Training*. OpenAI.
- Radford, A. et al. (2019). *Language Models are Unsupervised Multitask Learners*. OpenAI.
- Brown, T. et al. (2020). *Language Models are Few-Shot Learners*. arXiv:2005.14165.
- OpenAI (2023). *GPT-4 Technical Report*. arXiv:2303.08774.
- Ouyang, L. et al. (2022). *Training language models to follow instructions with human feedback*. arXiv:2203.02155.