sessionStorage Viewer — JSON Inspector
Parse and inspect sessionStorage data exported as JSON with type detection and size analysis.
How it works
- 1Paste or type your text in the input field
- 2Click "Process" — processing happens in your browser
- 3Copy the result or download as a text file
What to do next
About sessionStorage Viewer
sessionStorage Viewer is part of a collection of single-purpose web and productivity utility tools. Parse and inspect sessionStorage data exported as JSON with type detection and size analysis. Each tool is intentionally narrow — it does one thing well rather than offering many overlapping features — which makes the common path predictable and the result easy to verify before you download or copy it.
sessionStorage Viewer fits naturally into the workflow of teachers building resource lists and marketers running campaigns, both of whom typically need a fast result inside the browser. There is no learning curve to budget for: anyone who has used a typical web upload form can complete a run on the first try.
The right moment to reach for sessionStorage Viewer is when you have a focused web and productivity utility job that fits inside a browser tab. Open the page, drop in the file or paste your input, choose the options that matter, and the tool returns the result.
Internally the tool runs on standard browser APIs — the same processing stack used by professional desktop pipelines, just compiled for the browser. 0 MB is the practical ceiling, set so the tool stays responsive on phones and older laptops.
The browser sandbox isolates the page's JavaScript from the rest of the system, the same way it isolates every other tab you have open. sessionStorage Viewer works inside that sandbox: it reads the file you give it, processes it with standard browser APIs, and writes the result back. Nothing leaves the page's memory unless you choose to download or copy it.
Even on its own, sessionStorage Viewer composes well with the rest of your toolkit. The output is a standard web utility file that opens in any program that handles the format, so the result of one run can become the input to whatever step you use next.
The only practical limit is the 0 MB per-file ceiling, which keeps the tool responsive across a wide range of devices. Run the tool ten times in a row, run it ten thousand times — it behaves the same way and produces the same quality of result.
The transformation in sessionStorage Viewer is deterministic — the same input plus the same options produces the same result every run. That predictability matters when the result has to match an upstream specification or be reproducible later.
When the job finishes, sessionStorage Viewer hands you the result as a sensibly named file. Filenames are derived from your input where possible, so a quick batch of jobs leaves you with a tidy folder rather than a pile of generic "output (3)" files. Nothing is auto-saved on Favtoo's side because nothing was ever sent there.
sessionStorage Viewer is structured around the idea that a useful tool should be its own page. Open the page, do the work, close the tab — the page is the entire product. There is no onboarding flow because there is nothing to onboard into.
sessionStorage Viewer fits the gap where opening a desktop app feels heavy and writing a script feels overkill. The page handles the common web and productivity utility task with sensible defaults so a single visit usually completes the job; for highly specialised work, a dedicated desktop application can offer more knobs to turn.
Useful patterns when working with sessionStorage Viewer: keep the input file open in another tab so you can compare against the result; give the output file a descriptive name when saving so you can find it later (the default name is sensible but generic); and treat each run as independent — the tool has no concept of "history", which means you cannot accidentally pollute one job with leftovers from another.
For most failure modes, refreshing the page and re-running the job is enough — the engine has no persistent state to corrupt. If the same input fails twice in a row, the input itself is most likely the problem (a truncated file, an unexpected variant of the format, or a stream the engine does not recognise).
That is essentially everything sessionStorage Viewer does and how it does it. Open the tool above, drop in your input, and the work happens in the page. If you find yourself reaching for it often, bookmark the page — it loads quickly on subsequent visits, and your most-recent settings are remembered for the rest of the session.
How it works
- 1Open sessionStorage Viewer in your browser. The page loads quickly and the tool is ready to use the moment it becomes interactive.
- 2Select the web utility file you want to process — drag-and-drop and the file picker both work.
- 3Tweak the controls if the defaults are not quite right for your input. The options are kept short and labelled in plain language.
- 4Trigger processing. standard browser APIs reads your input, applies the transformation, and writes the result back into the page.
- 5Download the result. The file is generated in your browser and saved through your normal download flow.
- 6Re-run with different settings as often as you want. Each run produces a fresh output and the original file on disk is never modified.
Common use cases
- Create a placeholder image for a wireframe using sessionStorage Viewer.
- Generate a campaign asset in seconds for a quick test.
- Sanity-check a webhook response while debugging.
- Validate a setting before circulating it to a team.
- Compare two product variations side by side.
- Run a one-off check during a meeting without context-switching.
- Plan content without paying for a SaaS dashboard.
- Preview how a result looks before deploying it.
FAQ
How to export?
Run in console: JSON.stringify(Object.fromEntries(Object.keys(sessionStorage).map(k => [k, sessionStorage.getItem(k)])))
Difference from localStorage?
sessionStorage data is cleared when the tab or window is closed. localStorage persists until explicitly cleared.
Shared between tabs?
No — sessionStorage is unique to each tab, even for the same origin.
Private?
Yes — parsing runs locally.
Size limits?
Same as localStorage — typically 5 MB per origin per tab.
Use cases?
Common for CSRF tokens, form state, shopping carts, and temporary navigation state.
How do I run sessionStorage Viewer over a folder of files?
sessionStorage Viewer processes one input at a time by design — it keeps memory usage predictable on lower-end devices and makes results easier to verify. To handle a folder, run the tool once per file; the page stays loaded between runs and remembers your last-used settings, so the second run is essentially instant.
Which file formats does sessionStorage Viewer accept?
The accepted formats are listed in the upload area on the tool itself. If your input is in a format that is not directly supported, convert it first using one of Favtoo's converter tools — every Favtoo converter outputs a file that is a clean input to the next tool in the chain.
Can I use sessionStorage Viewer for commercial work?
sessionStorage Viewer can be used for personal and commercial work alike — there is no separate "business" licence to purchase. The output you generate is yours to use however you want, including in client deliverables, internal documents, or commercial products. Favtoo's only ask is fair, individual use; the tool is not designed to be embedded as a backend service or wrapped behind an API for resale.
Is there a desktop version of sessionStorage Viewer?
No installation is needed. sessionStorage Viewer runs as a normal web page, with no browser extension, no native helper, and no separate desktop client to download. That is partly a privacy choice — extensions can request broad permissions, while a regular page is sandboxed by default — and partly a convenience one: you can use sessionStorage Viewer on any computer you have temporary access to without leaving anything installed on it.
Are there any usage limits on sessionStorage Viewer?
Inputs are capped at 0 MB per file, which keeps memory usage stable across phones, tablets and older laptops. You can run sessionStorage Viewer as often as you need; every run produces a full-quality result.
How often is sessionStorage Viewer updated?
sessionStorage Viewer is updated whenever the underlying engine releases an improvement or a bug fix. Because the tool is delivered as a static page, every visit fetches the latest version automatically — there is no "version" to manage on your end. If a particular release ever changes default behaviour, the change is documented on Favtoo's changelog so you can confirm what shifted.
Is sessionStorage Viewer mobile-friendly?
sessionStorage Viewer runs in any modern mobile browser — Safari, Chrome, Firefox and the in-app browsers in most messaging apps all support the underlying APIs. Performance depends on the device: a recent phone handles typical inputs nearly as fast as a laptop, while older devices may take a few seconds longer near the 0 MB ceiling. The interface lays out cleanly on small screens, so you do not need to pinch-zoom to see the controls.
How long does Favtoo retain my data after using sessionStorage Viewer?
Favtoo keeps no copy of your file because Favtoo never receives your file. sessionStorage Viewer runs entirely in your browser, the input is held only in your tab's memory, and closing the tab discards it. There is no opt-in cloud history, no "recent jobs" panel synced to an account, and no server-side retention to configure — the architecture simply has nowhere for your file to be stored.
Which browsers are supported by sessionStorage Viewer?
sessionStorage Viewer works in any modern browser released in the last few years — Chrome, Edge, Firefox, Safari, Brave, Arc and the major Chromium derivatives are all supported. The underlying engine relies on widely-supported web APIs, so there is nothing exotic to install. If you are on a very old browser version and the tool fails to load, updating to the latest release of your preferred browser is the only fix needed.