The landscape of artificial intelligence is ever-shifting, with OpenAI consistently at the forefront of innovation. Recent months have brought significant changes, and more are on the horizon. While the official launch of the highly anticipated GPT-5 AI model remains unconfirmed, OpenAI is strategically reorganizing its existing model lineup, signaling a clear path toward its release. This includes phasing out some of its most popular models, such as GPT-4 and GPT-4.5.
GPT-4’s Retirement and the Rise of Reasoning Models
OpenAI’s decision to retire its GPT-4 AI model, effective April 30, marks a significant transition. GPT-4, a long-standing and widely used large language model, has been a cornerstone of OpenAI’s offerings. However, the company’s focus has gradually shifted away from traditional large language models toward a new generation of reasoning models and other advanced technologies.
In a series of intriguing moves, OpenAI introduced the GPT-4.1 model family, exclusively as an API for developers. Simultaneously, plans were announced to sunset the recently launched GPT-4.5 model, while also releasing the o3 and o4 reasoning models. These actions strongly suggest that the GPT-5 launch is imminent.
A Look Back at GPT-4’s Journey
GPT-4 was initially launched in March 2023 as the engine behind the ChatGPT Plus paid subscription, amidst the early fervor of the AI revolution. The introduction of ChatGPT Plus was a response to the overwhelming demand for the chatbot, which had placed a significant strain on OpenAI’s servers. ChatGPT Plus subscribers gained access to GPT-4, while free ChatGPT users continued to utilize the original GPT-3.5 model, which was launched during the initial introduction of the AI service.
OpenAI highlighted several key improvements between GPT-3.5 and GPT-4. These included an expanded context window, increasing from 2048 tokens to a substantial 128,000 tokens. GPT-4 also introduced the ability to upload images for analysis, generating text-based responses, and producing more creative and nuanced text outputs based on detailed prompts. Subsequent version updates to the GPT-4 model included GPT-4 Turbo, GPT-4 Turbo with Vision, GPT-4o, and GPT-4o mini. The GPT-4o mini model is currently the standard across all ChatGPT tiers. The advancements from GPT-3.5 to GPT-4 represented a significant leap in AI capabilities, demonstrating improved understanding, context retention, and creative generation. The increased context window allowed for more complex and nuanced conversations, while image analysis opened new avenues for AI interaction. GPT-4’s evolution culminated in versions like GPT-4o, pushing the boundaries of what’s possible with large language models.
The retirement of GPT-4 signifies a strategic shift towards more advanced and specialized AI models, reflecting OpenAI’s commitment to continuous innovation and pushing the limits of AI technology. This transition also underscores the rapid pace of development in the AI field, where models are constantly being refined and replaced with more capable alternatives. As GPT-4 sunsets, it leaves behind a legacy of groundbreaking achievements and contributions to the AI landscape, paving the way for even more sophisticated models like GPT-5. The decision to retire GPT-4 was not taken lightly. OpenAI carefully considered the impact on users and developers, ensuring a smooth transition to newer models. The company provided ample notice and resources to help users adapt to the changes, demonstrating its commitment to responsible AI development and deployment.
Reasoning Models: A New Paradigm
In December 2024, OpenAI embarked on an innovative journey with the introduction of reasoning models. This was part of their “12 Days of OpenAI” marketing campaign. The unveiling of the o1 reasoning model stood out as a pivotal moment. The introduction mirrored the public launch of their large language models, providing users with a comprehensive overview of this new form of AI. Reasoning models excel at logical thinking, providing insights into the thought processes behind AI-generated results. This contrasts with large language models, which are trained on vast datasets to deliver contextual responses to queries. During the “12 Days” event, OpenAI also launched the $200 per month ChatGPT Pro tier, making the o1 model exclusive to this subscription option.
Since then, OpenAI has released the o3 and o4-mini reasoning models. These models boast enhanced performance in coding, math, and science tasks compared to the o1 model. They are available within the $20 ChatGPT Plus tier, while the o4-mini model is also included in the free tier of ChatGPT. The development of reasoning models represents a significant departure from traditional large language models. While LLMs excel at generating text and understanding context, reasoning models focus on logical thinking and problem-solving. This allows AI to not only provide answers but also explain the reasoning behind them, making AI more transparent and understandable. The introduction of reasoning models reflects a growing emphasis on AI explainability and trustworthiness. As AI becomes more integrated into our lives, it’s crucial to understand how it arrives at its decisions. Reasoning models offer a window into the AI’s thought process, allowing users to evaluate its logic and identify potential biases. This transparency is essential for building trust in AI systems and ensuring they are used responsibly.
The launch of multiple reasoning models, each with its own strengths and capabilities, demonstrates OpenAI’s commitment to advancing this new form of AI. The o3 and o4-mini models, with their enhanced performance in coding, math, and science tasks, represent significant improvements over the initial o1 model. By offering these models at different subscription tiers, OpenAI is making reasoning AI accessible to a wider range of users, from casual users to professionals. This democratization of AI is crucial for fostering innovation and driving adoption of this technology across various industries.
GPT-4.5 and the Turing Test
Despite the company’s growing focus on reasoning models, OpenAI has continued to develop and release its LLMs. The launch of GPT-4.5 in late February 2025 marked a significant milestone as its largest AI model to date. One of the most notable features of GPT-4.5 was its reduced tendency to produce hallucinations, a persistent challenge for AI models. The model also demonstrated improved conversational and problem-solving abilities, as well as greater emotional intelligence. This enabled it to discern nuances in creativity across tasks such as writing and design. GPT-4.5 was made available to both ChatGPT Plus and ChatGPT Pro users.
The Turing Test Breakthrough
In early April 2025, reports emerged indicating that GPT-4.5 had passed the Turing Test, an intelligence evaluation conducted in a UC San Diego study. The test involved human participants tasked with identifying which model they believed was human and which was AI after a five-minute interaction. The researchers discovered that when the AI model was configured to emulate the profile of a “geeky 19-year-old knowledgeable about internet culture,” it was selected as human 73% of the time. Without a specific profile, the model was identified as human 36% of the time.
The Turing Test holds significant importance because it allows researchers to study the potential applications and ethical implications of AI in real-time. The study concluded that the GPT-4.5 model enabled humans to engage in meaningful and successful conversations with AI. The Turing Test breakthrough of GPT-4.5 was a landmark achievement in the field of AI. It demonstrated that AI models are becoming increasingly capable of mimicking human conversation and behavior, blurring the lines between human and machine intelligence. The ability to pass the Turing Test, especially when configured with a specific personality profile, highlights the potential for AI to be used in a wide range of applications, from customer service to companionship. However, the Turing Test also raises important ethical questions about the nature of intelligence, the potential for deception, and the impact of AI on human relationships. As AI models become more sophisticated, it’s crucial to consider these ethical implications and develop guidelines for responsible AI development and deployment.
The study conducted at UC San Diego provided valuable insights into how AI models are perceived by humans and how they can be tailored to create more believable and engaging interactions. The finding that GPT-4.5 was more likely to be identified as human when configured with a specific personality profile suggests that AI models can benefit from incorporating elements of human identity and culture. This could lead to the development of AI models that are more relatable, empathetic, and trustworthy.
The Abrupt Retirement of GPT-4.5
However, OpenAI surprised the AI community by announcing its decision to retire GPT-4.5 in mid-April, just months after its release. The company explained that the model did not meet the ‘frontier level’ of AI they were aiming for, which is defined as technology that surpasses current models. OpenAI plans to completely remove GPT-4.5 from its model lineup. Developers have been advised that they will have access to the API until July 14, with guidance provided for transitioning their projects to other APIs. The abrupt retirement of GPT-4.5, despite its impressive performance and Turing Test breakthrough, underscores the relentless pursuit of innovation at OpenAI. The company’s commitment to pushing the boundaries of AI technology means that even models that achieve significant milestones may be deemed insufficient if they don’t meet the highest standards of frontier AI. The decision to retire GPT-4.5 reflects a willingness to prioritize long-term goals over short-term gains, demonstrating a focus on developing truly transformative AI models.
The announcement of GPT-4.5’s retirement came as a surprise to many in the AI community, given its recent success and widespread adoption. However, OpenAI’s explanation that the model didn’t meet its ‘frontier level’ criteria provides valuable insight into the company’s strategic vision. By setting ambitious goals and consistently striving to surpass its own achievements, OpenAI is driving innovation in the AI field and pushing the limits of what’s possible. The decision to retire GPT-4.5 also highlights the rapid pace of development in the AI industry. Models that were considered state-of-the-art just months ago can quickly become obsolete as new and more capable models emerge. This constant evolution requires developers and users to be adaptable and embrace new technologies.
API Efforts and Developer Focus
While the consumer-facing GPT-4 model is nearing its end, OpenAI has emphasized that its API will remain available for developers. The company has not yet disclosed how it intends to utilize the protocol in the future, but it could offer a convenient platform for building consumer-focused AI tools. Several major companies, including Duolingo, Stripe, and Microsoft, have already leveraged GPT-4 to power AI features in their products. OpenAI also recently made its GPT-3.5 Turbo API available to developers. This is the base model that powered the ChatGPT chatbot when it was first introduced to the public in 2022. Similarly, brands such as Snap Inc., Quizlet, Instacart, and Shopify have utilized the API to create customer-facing AI features.
OpenAI has also introduced GPT-4.1 in the API, a model family targeted at developers. This family includes GPT-4.1, GPT-4.1 mini, and GPT-4.1 nano, offering the same functionality as GPT-4.5 but at a lower cost. OpenAI claims that it has performance updates over GPT-4o; however, it has no major improvements to be called a ‘frontier level.’ Even so, the model is knowledgeable up to June 2024. OpenAI has collaborated with brands including Windsurf, Qodo, Hex, Blue J, Thomson Reuters, and Carlyle to test GPT-4.1’s capabilities as its fastest and cheapest model. OpenAI’s focus on APIs and developer tools demonstrates its commitment to democratizing AI and empowering others to build innovative applications. By providing access to its powerful AI models through APIs, OpenAI is enabling developers to create a wide range of AI-powered solutions, from chatbots and virtual assistants to data analysis tools and content generation platforms. This ecosystem of AI applications is driving innovation and transforming industries across the globe.
The availability of different GPT models through APIs, each with its own strengths and capabilities, allows developers to choose the model that best suits their specific needs. The GPT-4.1 family, with its lower cost and comparable functionality to GPT-4.5, provides an attractive option for developers who are looking for a balance between performance and affordability. The collaboration between OpenAI and various brands to test GPT-4.1’s capabilities highlights the importance of real-world testing and feedback in the development of AI models. By working closely with developers and users, OpenAI can identify areas for improvement and ensure that its models are meeting the needs of the market.
Anticipating GPT-5: A Frontier Model
The AI community has long awaited GPT-5, and the efforts OpenAI has invested in its previous models could lead to significant improvements for this forthcoming AI model. While the company has not provided a specific launch timeline, a 2025 release appears increasingly likely. OpenAI indicated earlier in the year that GPT-5 could be available within the coming months.
Initial reports suggested that the AI model might be released sometime in May or during the summer. However, the recent release of the o3 and o4-mini reasoning models casts some doubt on this timeline. Nevertheless, OpenAI is known for its surprise announcements. Sam Altman, the company’s CEO, has even hinted on X (formerly Twitter) that there may be some changes to AI model naming conventions before GPT-5 is launched.
There are indications that OpenAI is striving to make GPT-5 a true frontier model, offering something entirely new and unique to the industry. Based on earlier criteria, GPT-4 is considered a frontier AI model. The reasoning models also hold this distinction, changing the way AI processes data. The anticipation surrounding GPT-5 reflects the transformative potential of AI and the excitement about what the future holds. As OpenAI continues to push the boundaries of AI technology, the AI community eagerly awaits the unveiling of GPT-5 and the groundbreaking capabilities it will bring. The hints and suggestions from OpenAI and its CEO, Sam Altman, have only fueled the speculation and excitement, creating a sense of anticipation that is palpable throughout the industry.
The focus on making GPT-5 a true frontier model suggests that OpenAI is aiming to create something that goes beyond incremental improvements and represents a significant leap forward in AI capabilities. This could involve new architectures, training techniques, or a combination of both. The success of GPT-4 and the introduction of reasoning models have set a high bar for GPT-5, but OpenAI appears determined to surpass expectations and deliver a truly revolutionary AI model.
Key Features of GPT-5
Altman has suggested that GPT-5 will feature autonomous AI agents that will assist users by independently executing tasks. Another anticipated feature is the ability of GPT-5 to select the best available model based on the user’s query.
Users on the free tier of ChatGPT are also expected to have limited access to the GPT-5 model. However, those with Plus and Pro subscriptions will be able to fully leverage the model’s advanced capabilities. The potential inclusion of autonomous AI agents in GPT-5 represents a significant step towards more intelligent and proactive AI systems. These agents could assist users with a wide range of tasks, from scheduling appointments and managing emails to conducting research and making recommendations. The ability of GPT-5 to select the best available model based on the user’s query would further enhance its versatility and adaptability, allowing it to tailor its responses to the specific needs of each user.
The tiered access to GPT-5, with limited access for free users and full access for Plus and Pro subscribers, reflects OpenAI’s strategy of balancing accessibility with revenue generation. This approach allows OpenAI to provide a free version of its AI models to a wide audience while also generating revenue from users who require more advanced capabilities. This model has proven successful in the past and is likely to continue to be a key part of OpenAI’s business strategy.