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Mixed

Published fact-check

GPT-5.5 'Spud' in Testing and Comparison to Claude Opus 4.7

Claim checked

“Yep. GPT-5.5 has been in testing on ChatGPT for a few days now, and I can confirm it’s better than Opus 4.7.”

Published April 19, 2026 at 1:46 PM

Verdict

Mixed

While evidence confirms that GPT-5.5 (code-named "Spud") is a real model nearing release and Claude Opus 4.7 was recently launched, the claim that GPT-5.5 is currently being "stealth tested" on ChatGPT is unverified.

  • GPT-5.5 Status: OpenAI executives confirmed pretraining was completed in late March 2026, with a release expected in Q2 2026.
  • Opus 4.7 Status: Anthropic released Claude Opus 4.7 on April 16, 2026.
  • Performance: There are no official benchmarks comparing the two, as GPT-5.5 has not been publicly released for side-by-side testing.

3 reviewed sources behind this verdict.

Reasoning

The claim contains three distinct parts: the existence of the models, the current testing status, and a performance comparison.

  1. Existence: Supported. Sources confirm GPT-5.5 (Spud) is OpenAI's next model and Opus 4.7 is Anthropic's latest general release.
  2. Testing: Unverified. While Sam Altman stated in March 2026 that the model was "a few weeks" away, there is no official confirmation from OpenAI that it is currently live for stealth testing on the web as of April 19, 2026.
  3. Comparison: Unverified. Because GPT-5.5 is not yet public, any claim that it is 'better' than Opus 4.7 is based on anecdotal user experience or speculation rather than verified benchmarks.

Source quality: The evidence includes detailed reporting from The Verge and Silicon Republic regarding the release of Opus 4.7 and the development of GPT-5.5. However, it lacks official confirmation of the 'stealth testing' mentioned in the social media post.

Key checks

  • Release of Claude Opus 4.7: Anthropic released Claude Opus 4.7 on April 16, 2026. It is described as an improvement over Opus 4.6 for coding and image analysis but less powerful than their private 'Mythos' model.

  • Status of GPT-5.5 (Spud): OpenAI completed pretraining for GPT-5.5 (code-named 'Spud') around March 24, 2026. CEO Sam Altman indicated a release would occur in 'a few weeks,' placing the expected window in April or May 2026.

  • Stealth testing on ChatGPT: There is no official documentation or verified reporting confirming that GPT-5.5 is currently active for users on the ChatGPT web interface as of April 19, 2026.

Confidence

High