localStorage Viewer — JSON Inspector
Parse and inspect localStorage data exported as JSON with type detection and storage quota 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 localStorage Viewer
localStorage Viewer is shaped around how people actually use web and productivity utility utilities online: open the page, drop in a file, get the result. Parse and inspect localStorage data exported as JSON with type detection and storage quota analysis. The interface stays out of the way once the work begins so the engine can use the available CPU and memory for the actual transformation.
localStorage Viewer fits naturally into the workflow of analysts pulling lightweight reports and creators experimenting with formats, 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.
Reach for localStorage Viewer when you need a predictable result on a single file. The page works on the first visit, the controls are visible without a menu, and the output is delivered the moment the engine finishes.
localStorage Viewer runs on standard browser APIs — an open-source, well-audited engine that performs the web and productivity utility natively in the browser. It accepts the formats listed in the upload area and produces output that opens in any standard web utility viewer. Per-run input is capped at 0 MB.
Because everything runs in the page, the tool scales the same way for one user or a million — there is no per-user backend cost. The page is static, the engine is the same JavaScript bundle for every visitor, and the work happens on the visitor's own device. That keeps the tool free and keeps it fast on the first interaction.
localStorage Viewer fits naturally next to several adjacent tools. Common companions include sessionStorage Viewer, IndexedDB Viewer, Cookie Viewer, and Cookie Analyzer — combine them when the job needs more than one transformation. After running localStorage Viewer, many users move on to sessionStorage Viewer and IndexedDB Viewer. Each tool is a separate page so you can compose the exact pipeline you need.
A practical note on limits: localStorage Viewer accepts inputs up to 0 MB per run, and the tool processes one input at a time to keep memory usage predictable. If you ever bump into the ceiling, the cause is the size of the input.
The transformation in localStorage 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, localStorage 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.
localStorage Viewer is one example of a broader pattern: utility software increasingly works as single-page, client-side experiences. Every page in the catalog is shaped that way, which keeps each tool fast to load and easy to recommend in a single link.
localStorage Viewer is built around the moment of need: a focused page you open when you have a specific task, complete the task, and close. The catalog contains many adjacent tools so the same model serves the surrounding parts of a typical web and productivity utility workflow.
Tips from users who reach for localStorage Viewer regularly: process one input first to confirm the settings produce what you expect before committing to a batch; treat the page as the working surface and avoid leaving large jobs running in a backgrounded tab where the browser may throttle JavaScript; and if a particular file fails, check whether the source is intact by opening it in its native viewer — most "tool errors" are actually input errors.
Common gotchas worth flagging: the supported formats are listed in the upload area. The 0 MB ceiling is per-file, not per-session; you can run as many separate jobs as you like, but a single oversized input will be rejected on load.
That is essentially everything localStorage 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 localStorage Viewer in your browser. The page loads quickly and the tool is ready to use the moment it becomes interactive.
- 2Add your web utility input by dropping it onto the page or browsing for it.
- 3Adjust the options to match what you need. Sensible defaults cover the most common case, so you can usually skip this step.
- 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.
- 6Repeat the process for additional inputs whenever you need to. The page stays loaded, so subsequent runs are quick.
Common use cases
- Sanity-check a webhook response while debugging using localStorage Viewer.
- Generate a campaign asset in seconds for a quick test.
- Create a placeholder image for a wireframe.
- Compare two product variations side by side.
- Run a one-off check during a meeting without context-switching.
- Run a fast accessibility check before publishing.
- Validate a setting before circulating it to a team.
- Plan content without paying for a SaaS dashboard.
- Generate a temporary asset for a social post.
FAQ
How to export?
Run in console: JSON.stringify(Object.fromEntries(Object.keys(localStorage).map(k => [k, localStorage.getItem(k)])))
Size calculation?
JavaScript strings use UTF-16, so each character is 2 bytes. Size is shown in both chars and KB.
Quota?
Most browsers allow 5-10 MB per origin. Usage percentage is calculated against 5 MB.
Private?
Yes — parsing runs locally.
Nested JSON?
String values that contain JSON are automatically parsed and pretty-printed.
Clearing?
Use localStorage.clear() in console or DevTools Application tab to clear all entries.
Does localStorage Viewer support batch processing?
localStorage 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.
Do I need to install anything to use localStorage Viewer?
No installation is needed. localStorage 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 localStorage Viewer on any computer you have temporary access to without leaving anything installed on it.
Is localStorage Viewer mobile-friendly?
localStorage 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.
Does localStorage Viewer match what professional tools produce?
localStorage Viewer is built on standard browser APIs, which is the same class of engine used by professional web and productivity utility pipelines. For deterministic operations, the output is byte-identical to what an equivalent CLI run would produce; for operations involving a codec or a model, the result is well within the range of what comparable tools generate. If you have a specific reference output you need to match, run a small test job first to confirm the configuration produces what you expect.
How often is localStorage Viewer updated?
localStorage 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.
Can I use localStorage Viewer for commercial work?
localStorage 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.
Why does localStorage Viewer feel slow on large inputs?
Most jobs finish in seconds. Speed scales with input size and with how many CPU cycles your browser tab has available — the engine runs in your browser, so it shares resources with whatever else you have open. For inputs near the 0 MB ceiling, expect anywhere from a few seconds to roughly a minute on a typical laptop. Closing other heavy tabs noticeably speeds things up.