Shortlist by what you need
Start here if you know why you are leaving iGPT.
Want the closest match?
OnyxMost similar to iGPT in what it does, its category and its price.
Visit (opens Onyx in a new tab)Need a free plan?
ShortwaveHas a free plan, rated 4.4 out of 5.
Visit (opens Shortwave in a new tab)Want the best rated?
Knowbase.aiRated 3.8 out of 5 in our review, against 3.6 for iGPT.
Visit (opens Knowbase.ai in a new tab)
At a glance
Green means better than iGPT, red means worse. Prices are starting prices per month.
| Tool | Our rating | Starts at | Free plan | Best for | Compare |
|---|---|---|---|---|---|
 iGPTBaseline | 3.6 | Free | Yes | Rebuilds a full email thread from scattered messages and cites its sources back to them. | |
| Onyx | 4.2+0.6 | $20/mo | Yes | Open-source AI chat and enterprise search that connects to a team's documents, apps, and people. | vs iGPT |
 Sidekick AI | 3.7+0.1 | Free | Yes | Forward a meeting email to it and it books the meeting for you. | vs iGPT |
| Knowbase.ai | 3.8+0.2 | Free | Yes | Knowledge base that answers from your own documents with citations back to the source. | vs iGPT |
 Saidar | 3.5−0.1 | Free | Yes | An email and calendar assistant you talk to in iMessage, with no app to open. | vs iGPT |
| Shortwave | 4.4+0.8 | $7/mo | Yes | An AI-native email client built by former Google engineers | vs iGPT |
The alternatives in detail
In order of how closely each one matches iGPT.
Onyx
4.2$20/mo
vs iGPT+0.6
Open-source AI chat and enterprise search that connects to a team's documents, apps, and people.
- Hybrid search plus RAG chat over 40+ connected workplace applications
- Self-hosted, MIT-licensed open-source core with full data control
- MCP support for connecting external tools and agent workflows
Free, license-unrestricted self-hosted option for teams that want to avoid sending data to a vendor
Self-hosting the open-source edition still requires infrastructure and maintenance effort
Sidekick AI
3.7Free
vs iGPT+0.1
Forward a meeting email to it and it books the meeting for you.
- Forward to Schedule from an email thread
- Individual and team booking pages
- AI time-finding across multiple participants
Forwarding fits the cases where sending a booking link is awkward
No pricing figures published for paid tiers
Knowbase.ai
3.8Free
vs iGPT+0.2
Knowledge base that answers from your own documents with citations back to the source.
- Answers cited back to the source document
- Chat across a whole document collection
- Transcript handling alongside documents
Citations make answers checkable rather than trusted blindly
A confident citation of the wrong passage looks like a correct one
Saidar
3.5Free
vs iGPT−0.1
An email and calendar assistant you talk to in iMessage, with no app to open.
- Email and calendar management over iMessage
- Daily schedule summaries
- Surfaces messages needing a decision
Lives in a thread you already have open, removing a step rather than adding one
Needs standing access to your email and calendar, a very large grant
Shortwave
4.4$7/mo
vs iGPT+0.8
An AI-native email client built by former Google engineers.
- AI-native email client built from scratch
- AI-powered search and thread summarization
- Built by former Google engineers
Genuinely rebuilt email experience, not a plugin on a traditional client
More features require a paid plan
FAQ
Questions people ask
Is iGPT free?
iGPT has a free plan.
What is the best free alternative to iGPT?
Shortwave is the highest-rated alternative here with a free plan (4.4 out of 5). Other free options: Onyx, Knowbase.ai, Sidekick AI.
What is the cheapest alternative to iGPT?
Among paid plans, Shortwave has the lowest starting price (from $7/mo). If you need it free, start with Shortwave.
How did you pick these alternatives?
We match tools on what they do, their category and their price, using the details in our directory. Ratings come from our reviews and reader reviews.