Series Overview
Part 1 | Why Does AI Get Things Wrong So Convincingly?
Part 2 | Why the OXMV Loop and Evidence Ledger Are Necessary
Part 3 | Mapping Knowledge for AI with Ontology
Part 4 | OpenAI to End ChatGPT’s Custom GPT Era on December 11, 2026
By Manripungchwi Jung Yeon-tae
On September 11, 2026, OpenAI made a significant announcement. It plans to retire the custom GPTs that users have built and operated within ChatGPT and move toward a new structure centered on plugins.
OpenAI’s official FAQ lists December 11, 2026, as the scheduled retirement date for custom GPTs. After that date, custom GPTs are expected to stop running. OpenAI says it will provide a migration path for transferring existing GPT instructions, reference files and connected capabilities to plugins.
The decision is striking when viewed against the enthusiasm of just three years ago. When OpenAI introduced custom GPTs in 2023, the world embraced the idea. People without coding skills could place their knowledge, documents, working methods and philosophy into an AI system and build a specialized GPT of their own.
Legal, medical, educational, travel, financial, research and enterprise GPTs appeared. These were more than simple chatbots. People began placing their experience and professional knowledge inside AI systems. We called them “personal AI,” “specialized agents” and “AI employees.”
In early 2024, OpenAI announced that users worldwide had already created more than 3 million custom GPTs. Although the company has not disclosed an updated cumulative figure, the number demonstrated how quickly the GPT ecosystem had expanded. OpenAI has now declared that this ecosystem will be retired.
Strictly speaking, the age of AI agents itself is not ending. OpenAI appears to be positioning ChatGPT as the central agent, supported by a combination of plugins, skills and connected apps. From the user’s perspective, however, the issue is not so simple. A platform that encouraged the creation of millions of GPTs is retiring the underlying structure only a few years later.
This Is More Than a Feature Change
OpenAI says users will be able to migrate custom GPTs to plugins. Plugins offer a new way to combine reusable instructions with connected apps. The company’s explanation is that existing GPT workflows will move to a different structure rather than simply being discarded. From OpenAI’s perspective, the change may be technically defensible.
The situation looks different from the perspective of a GPT builder. Creating a GPT involves far more than writing a few lines of prompts. It can require professional knowledge, dozens of knowledge files, operating procedures and validation rules. Prompt-injection defenses, connections to APIs and external services, and extensive trial and error may also be involved.
Some GPTs take months to develop. Others are completed only after hundreds of questions and validation tests. For one person, a GPT may have been a hobby; for another, it was a research tool. For a company, it may have become an operating system, while for a developer, it represented a future business.
Is it sufficient to explain the retirement of such an ecosystem by saying that users can simply move to a new plugin? I do not believe it is.
The Most Serious Issue Is Trust, Not Technology
Technology changes, and software evolves. Retiring an old structure when a better one emerges is common in the technology industry. A platform operator, however, differs from an ordinary software company because large numbers of people build their businesses, knowledge systems and futures on top of its platform.
OpenAI actively encouraged users to create GPTs. It launched the GPT Store and invited people to build their own GPTs. Developers and users trusted that invitation and invested their time and professional knowledge.
Only a few years later, the platform’s core structure is changing. That creates a fundamental question for developers: “Could plugins also disappear in a few years?”
This is the central issue in the current transition. Trust in an AI platform involves more than security. It also depends on the platform’s sustainability and predictability. How deeply can a developer place a company’s core operations and knowledge on a platform whose continued existence three years from now cannot be assured? OpenAI must answer that question.
Who Declared the Arrival of the Agent Era?
What terms have appeared most frequently across the AI industry in recent years? Agent. Agentic AI. AI agent. Multi-agent system. Autonomous agent. AI worker. AI copilot.
The entire world has been discussing agents. We were told that AI would advance beyond answering questions and begin performing work. It would understand user intent, search independently, make judgments, use tools and collaborate with other AI systems. Custom GPTs became the most widely accessible testing ground for that transition.
When experts placed their knowledge inside a GPT and assigned it a specific role, a small specialized agent was created. That structure is now being retired.
This does not mean that OpenAI has abandoned agents. The opposite may be true. OpenAI appears to be moving away from treating each GPT as an independent agent and toward making ChatGPT the primary agent, with plugins and skills operating beneath it.
The previous structure worked as follows:
User → selects a specific GPT → GPT runs
The future structure is likely to look more like this:
User → ChatGPT → selects the necessary plugin or skill → external tool runs
OpenAI’s official FAQ explains that ChatGPT may automatically select an installed plugin or skill when it matches a user’s request. This represents more than a feature change. It can be understood as a structural shift in which the center of the AI ecosystem moves from GPTs created by individual builders back to OpenAI’s core ChatGPT platform.
Does This Ultimately Strengthen Platform Control?
A hard business question must be asked. Which world is more advantageous to OpenAI: one containing millions of independent GPTs, or one in which a single ChatGPT selects and uses numerous plugins and skills? The latter is likely to offer greater advantages.
Keeping ChatGPT at the center makes models easier to manage. Tool use can be controlled, while security and authorization can be centralized. Connections to corporate data can be organized more systematically, and pricing structures may become simpler. The platform also gains greater control over which capabilities are invoked under particular circumstances.
The decision is technically rational. It may also make business sense. Yet a choice that is rational for a company is not necessarily the best choice for its users.
Based on the information currently available, it is impossible to conclude whether this decision is primarily a technical innovation intended to improve the user experience or a business restructuring designed to strengthen OpenAI’s platform control. It is difficult to rule out the possibility that both objectives are present. That is why a more transparent explanation is necessary.
What Happens to the Promise of the GPT Store?
When the GPT Store first appeared, people anticipated the arrival of a new AI app store. They believed anyone would be able to turn professional expertise into a GPT and distribute it worldwide. Many builders expected to create new businesses and revenue models based on specialized GPTs. Custom GPTs themselves are now disappearing.
OpenAI says existing GPTs can be migrated to plugins. Yet too many important questions remain unanswered from the builder’s perspective. What will happen to the GPT Store’s existing public distribution structure? How will plugins be published and distributed?
How will monetization work? How will search rankings and visibility be determined? If ChatGPT automatically selects plugins, how will users discover a plugin created by an independent developer? Will the brand and identity associated with an existing GPT be preserved?
The market has not yet accumulated enough experience to answer these questions. The confusion among builders is therefore understandable.
Migration Does Not Solve Everything
OpenAI is advising users to migrate their existing GPTs to plugins. Important limitations remain. According to the official FAQ, integrations built with Custom Actions will not be transferred automatically. OpenAI advises the creators of those GPTs to allow more time for migration preparations.
The original version of a migrated GPT can remain available until the retirement date, but it will become read-only. The more complex the GPT, the greater the migration challenge.
A basic knowledge-based GPT is very different from a GPT that uses external APIs, retrieves real-time data, connects to internal corporate systems or contains dozens of knowledge files. Their migration requirements and levels of difficulty are not comparable. The word “migration” should not create the impression that an ecosystem of millions of GPTs will move naturally and effortlessly into the new structure.
Builders must test each GPT again. They must ask questions, compare results and identify errors. Some GPTs will require redesign. Builders will ultimately bear the cost.
The Preparation Period Is Another Concern
The schedule presented in OpenAI’s official FAQ is fast. Preparation guidance was issued on September 11, 2026, while the creation of new custom GPTs is scheduled to end on October 26, followed by the retirement of custom GPTs on December 11. OpenAI also notes that the schedule may change and that the applicable timeline may vary by account or workspace.
The question is whether this period is sufficient to transition an ecosystem in which more than 3 million GPTs had already been created. It may be manageable for an individual with a few GPTs built as a hobby. Several months is not a long period for people operating dozens of specialized GPTs or companies that have integrated GPTs into their business operations.
Technology companies move quickly. A company that has created an ecosystem cannot move only at its own speed. Doing so risks transferring the cost of platform change to users.
This Is a Test of Platform Trust, Not the Death of GPTs
AI agents themselves will not disappear on December 11. More precisely, the first mass-market era in which users could directly create and independently operate their own specialized AI through custom GPTs is coming to an end. A new plugin era is beginning.
The new structure may prove superior. Combining plugins, skills, external apps and connected data could create agents far more capable than existing GPTs. There is no reason to dismiss that possibility.
For now, however, it remains a possibility. The retirement of the existing GPT ecosystem is already a decision. What users need now is not promotional language.
Why is the new structure better? What will existing builders gain, and what will they lose? How much of their investment will be preserved? How will publication and monetization work?
Will plugins remain a sustainable structure over the long term? OpenAI must provide much more specific answers to these questions.
In the AI Era, the Most Important Asset Is Your Own Knowledge
This episode carries an important lesson. No platform lasts forever. GPTs change, and plugins may eventually change as well. Models, user interfaces and corporate strategies also change.
The assets that truly need protection are not tied to a particular platform. They include knowledge files, ontologies, operating processes and prompts. Validation systems, data, user experience and an independent philosophy for designing AI are equally important.
These assets should be managed separately from the platform. Users can work with ChatGPT without becoming completely dependent on it.
What Ends on December 11, 2026?
If the schedule proceeds as planned, custom GPTs will stop working on that date. The more important question is what will begin. OpenAI is preparing to launch a new agent ecosystem centered on plugins. Time will determine whether that choice was right.
One point is already apparent. This decision will test more than OpenAI’s technical capability. It will also test the company’s responsibility toward the people who trusted its platform and invested their time, knowledge and businesses in it.
The strongest company in the AI era may not be the company with the largest model. It may be the company that convinces users they can safely entrust it with their future.
December 11, 2026, may prove to be more than the day custom GPTs are retired. It may mark the beginning of a new contract of trust between OpenAI and millions of GPT builders.
About the Author
Manripungchwi Jeong Yeon-tae is a professional-knowledge AI planner, designer, and GPT development specialist. He currently serves as President of the Construction Industry Information Institute and develops professional GPTs across construction, law, taxation, finance, management, medicine, science, history, and philosophy. His research focuses on verified professional-knowledge AI combining ontology, XAI, the OXMV Loop, and the Evidence Ledger.
