Your Astrology GPT Is Retiring on December 11. Here Is the Plugin That Replaces It.

If you use an astrology GPT in ChatGPT, it has a shutdown date. OpenAI's help center says custom GPTs are scheduled to retire on December 11, 2026. On that day the GPTs and their pages become inaccessible. Workspaces with an approved Enterprise deferral get until February 11, 2027.

I checked those dates against OpenAI's custom GPT retirement FAQ on the day I wrote this, October 25, 2026. If you read this later, check that page again, because OpenAI says the dates can change.

Which Astrology GPTs Are Affected

All of them. That includes the ones people found through the GPT store, such as Astrology Birth Chart GPT, long listed near the top of the store's astrology GPTs. When we last looked it was already inactive. Smaller birth chart and horoscope GPTs go the same way unless their creators migrate them, and a creator who migrates still has to make the replacement available to you.

I am not going to list other GPTs by name with conversation counts I cannot verify. If yours is not named here, the rule is the same: if a person built it as a custom GPT, it retires on the date above.

What You Lose

Less than you might fear, and more than the headline suggests.

• Your old conversations stay readable. OpenAI says existing conversations with custom GPTs remain accessible after retirement.
• The GPT itself goes away. You can no longer open it and start a new chat with it.
• Custom actions do not transfer. Many astrology GPTs got their chart data by calling an outside service. OpenAI says those connections are not migrated and have to be rebuilt.
• There is no automatic forwarding. Access to the old GPT does not give you access to a replacement. A creator's new plugin starts private, and making it public takes a separate submission.

That last point is the real problem. Millions of conversations happened in these GPTs, and nothing routes those people anywhere. You will have to go looking.

The Replacement

Open Ephemeris is a ChatGPT plugin that does the one thing most astrology GPTs could not do reliably: calculate the chart. Every position is computed from the NASA JPL DE440 ephemeris, to sub-arcsecond precision. ChatGPT does the talking. Open Ephemeris does the math.

It covers what people used those GPTs for: natal charts, rising sign, transits, synastry, Human Design bodygraphs, moon phases and eclipses. The wheel, the bodygraph and the moon dial draw inside the conversation.

Install It in Three Steps

1. Open the listing. Open Ephemeris is in the ChatGPT app directory.
2. Click Install plugin. ChatGPT asks you to sign in to Open Ephemeris. That creates a free account. No card, no download.
3. Type @Open Ephemeris in any chat and ask in your own words, for example @Open Ephemeris draw my full birth chart.

It works on every ChatGPT plan, free included. If you are about to lose a GPT you liked, this takes about two minutes, and you can do it today while the old one still works. That is the best way to compare them.

Why the Calculation Matters

Here is the test that convinced me. I asked ChatGPT, with no plugin, for the rising sign of someone born July 15, 1987 at 9:01 AM in Chicago. After working for 14 seconds it answered 3° Pisces, then wrote a full "Big 3" reading on top of it.

The correct Ascendant is 3°02' Virgo. That is JPL DE440, Placidus houses, local time resolved through America/Chicago to 14:01 UTC.

Pisces is exactly opposite Virgo. ChatGPT gave the Descendant, the point 180° away from the one asked for, with confidence. Every sentence after that was built on the wrong horizon.

This is not a flaw in any one GPT. A language model has no planetary table inside it, and a degree is not something you can reason your way to. A GPT that does not call a real ephemeris is estimating. A GPT that does call one needs that connection rebuilt after December 11. Either way, the plugin route fixes the number.

One honest caveat: the model still writes the prose around the result. If the wheel and a sentence ever disagree, trust the wheel, which is drawn from the computed longitude.

If You Built a GPT

If you are the creator of an astrology GPT, your instructions can move into a plugin skill, and Open Ephemeris can replace your custom action. A guide for that is in the works. For now, the install page shows the tools your plugin would have access to.