Privacy-first data analysis: nothing leaves your browser
If a file has customer names, internal numbers, or anything you'd rather not hand to a third-party server, the safest way to analyze it is to never upload it in the first place. That's the default in Synth, not an opt-in setting.
Lite Mode: no account, nothing sent anywhere
Open Synth and you're in Lite Mode by default. Upload a CSV or JSON file and it's parsed directly into a real SQLite database running in your browser tab's memory — there's no server in the loop at all. No sign-in, no account, and nothing about the file or its contents is transmitted anywhere.
| Lite Mode | Normal Mode | |
|---|---|---|
| Account needed | No | Yes (free) |
| Where your file lives | Your browser tab only | Your browser, plus cloud if you save |
| Session persists after closing tab | No | Yes, if saved |
| Best for | A one-time, sensitive, or throwaway file | A dataset you'll come back to |
Switching to Normal Mode — a free sign-in — is there when you actually want to save a workspace and pick it up on another device. It's never required to start.
The AI assistant follows the same rule
Turning on the built-in AI assistant doesn't change this. In either SQL Mode or General Mode, only your table's schema — column names, types, and row count — is sent to generate a response. Your actual row values are never included in that request, and every query still executes locally against the SQLite database in your tab. See how the AI assistant works for the full detail.
What "saving to the cloud" actually means
If you do sign in and explicitly save a workspace, that file's contents move to Synth's cloud storage so you can reopen it on another device — this is opt-in, and clearly a different action from analyzing the file, which never requires it. Nothing about querying, the AI assistant, or exploring your data pushes you toward saving unless you choose to.
Who this matters for
- Analyzing an HR, payroll, or customer export you shouldn't be uploading to a random web tool
- Working with data under an NDA or compliance requirement that restricts where it can go
- Just not wanting a one-off file to sit on someone else's server after you're done with it
Frequently asked questions
Does Synth upload my file to a server?
Not by default. In Lite Mode, your file is parsed and loaded into a SQLite database entirely inside your browser tab — nothing is sent anywhere. It's only uploaded if you explicitly sign in and choose to save your workspace to the cloud.
Do I need to create an account to analyze my data privately?
No. Lite Mode requires no sign-in at all — upload a file and start querying immediately. Signing in (Normal Mode) is an optional upgrade for saving your session across devices, never a requirement to start.
Does the AI assistant see my actual data?
No. Only your table's schema — column names, types, and row count — is sent to generate a response. Your actual row values never leave your browser, in either AI mode.
What happens to my data if I close the tab in Lite Mode?
It's gone, by design — Lite Mode keeps everything in browser memory for that session only. If you want your workspace to persist across sessions or devices, sign in and save it (Normal Mode); nothing is saved automatically.