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Feature checklists make every tool look equivalent. This table leads with the three things that actually differ — what it costs you before it works, whether your files leave your device, and where the free version stops.
| regex101regex101.com | jwt.iojwt.io | Bundlephobiabundlephobia.com | Can I Usecaniuse.com | |
|---|---|---|---|---|
| What it does | Builds and explains a regular expression while you type it | Decodes a JSON Web Token into readable header, claims and signature | Shows what an npm package costs your bundle before you install it | Answers whether a browser feature is safe to ship yet |
| What it costs you | No sign-upWorks the moment the page loads. No account, no email, no trial. | No sign-upWorks the moment the page loads. No account, no email, no trial. | No sign-upWorks the moment the page loads. No account, no email, no trial. | No sign-upWorks the moment the page loads. No account, no email, no trial. |
| Your files | Runs on their server | Runs on your device | Runs on their server | Runs on their server |
| Where it stops | Long inputs and catastrophic backtracking hit an execution timeout rather than completing. | It decodes and verifies but is not a key manager — there is nowhere to store or rotate the keys you paste. | Figures assume you import the whole package, and very recent versions may not be analysed yet. | Support data is community-maintained and can trail an actual browser release by weeks. |
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| Category | Developer & Code | Developer & Code | Developer & Code | Developer & Code |
| Last checked | 2026-07-29 | 2026-07-29 | 2026-07-29 | 2026-07-29 |
| Open the site | Open | Open | Open | Open |
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