TOTP Validator — Check OTP Code Format
Validate TOTP code format by checking digit count and numeric composition for quick format verification.
How it works
- 1Paste or type your text in the input field
- 2Click "Validate" — processing happens in your browser
- 3Copy the result or download as a text file
What to do next
About TOTP Validator
TOTP Validator is part of a collection of single-purpose developer utility tools. Validate TOTP code format by checking digit count and numeric composition for quick format verification. 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.
Under the hood, TOTP Validator uses standard browser APIs to do the actual work. Input runs through the same engine, with a per-file ceiling of 0 MB so memory usage stays predictable on lower-end laptops and tablets. The engine ships as part of the page bundle, so once the page is loaded the tool keeps working even if your network connection drops.
The right moment to reach for TOTP Validator is when you have a focused developer 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.
The architecture is local-first by design. Once the page is loaded, you can disconnect from the network and the tool still completes the job. The processing stack — standard browser APIs and the small UI shell wrapping it — ships with the page itself, so the tool keeps working in offline conditions, on a captive-portal Wi-Fi, or behind a corporate proxy that limits what the tab can reach.
The hard constraints are easy to remember. Maximum input: 0 MB. Multiple files per run: no — one input at a time, by design, to keep results predictable. The same controls apply on every run.
TOTP Validator is intentionally narrow in what it does, which makes it easy to slot into a longer workflow. Take its output, hand it to whichever next tool fits the job, and TOTP Validator stays out of your way until the next time you need it.
TOTP Validator is shaped around the recurring needs of two audiences: backend developers inspecting requests, who use it as a quick utility between bigger tools, and site reliability engineers triaging logs, who use it as their primary way of getting the job done. Both groups get the same defaults and the same speed.
When the job finishes, TOTP Validator 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.
TOTP Validator is honest about scope: it handles a single, well-defined developer utility step. Specialist edge-case work — uncommon formats, very large inputs, or pipelines that need scripting — is what dedicated desktop apps are for. This page handles the common case quickly.
TOTP Validator 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.
Useful patterns when working with TOTP Validator: 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.
TOTP Validator fits the gap where opening a desktop app feels heavy and writing a script feels overkill. The page handles the common developer 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.
If TOTP Validator appears to hang, the engine is almost certainly still working — large inputs simply take longer to process inside a browser than they would on a server with multi-core scheduling. For inputs near the 0 MB cap, give it up to a minute on a typical laptop before assuming something is stuck.
That is the whole tool. Use TOTP Validator for as long as it stays useful to you, and if it does, the catalog has many more tools built the same way. Each applies the same single-purpose discipline, so the way you used this page transfers to the next one you try.
How it works
- 1Land on the TOTP Validator page. The tool is ready to use the moment the page renders.
- 2Select the developer file you want to process — drag-and-drop and the file picker both work.
- 3Pick any non-default settings you need. Most users leave the defaults alone for the first run and only revisit if the result needs tuning.
- 4Click to start the job. The engine (standard browser APIs) processes the input in the page; you can watch the progress indicator until it completes.
- 5Grab the output as soon as the run completes. You can also copy the result instead of downloading if the next tool in your workflow accepts pasted input.
- 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
- Convert between data formats while wiring up an integration using TOTP Validator.
- Inspect a regex against a test string before committing it.
- Generate boilerplate from a single specification line.
- Validate a config blob before pushing to staging.
- Decode a token to confirm its claims during a debugging session.
- Compare two API responses to spot a regression.
- Inspect a payload during local development without writing a script.
- Generate a quick fixture without leaving the browser.
- Encode binary content for transport in a JSON body.
- Hash a string for a quick reproducibility check.
FAQ
Does this verify the TOTP against a secret?
No — this tool only validates the format (length and character set). Actual TOTP verification requires the shared secret key and current time.
What formats are valid?
Standard TOTP codes are 6 or 8 digits (numeric only), as defined in RFC 6238.
Can I validate HOTP codes too?
HOTP codes follow the same format (6 or 8 digits), so this validator works for both TOTP and HOTP format checking.
Is my code sent anywhere?
No — validation runs entirely in your browser. Your code never leaves your device.
Why is my code invalid?
Common reasons include non-numeric characters, spaces, or the code being a length other than 6 or 8 digits.
What about alphanumeric TOTP codes?
The standard TOTP algorithm always produces numeric codes. If you have alphanumeric codes, they may use a different protocol.
Does TOTP Validator work on a phone or tablet?
TOTP Validator 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 TOTP Validator require a browser extension or plug-in?
No installation is needed. TOTP Validator 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 TOTP Validator on any computer you have temporary access to without leaving anything installed on it.
What does TOTP Validator do that command-line tools do not?
Desktop apps usually have more advanced features but require installation, maintenance and (often) a licence. Paid online tools are convenient but route your file through their servers and gate downloads behind accounts. TOTP Validator sits in between: free, instant, and private, but intentionally narrow in scope. For one-off jobs and the common developer utility operations, it is usually the lowest-friction choice; for highly specialised work, a dedicated app is still the right answer.
How many times per day can I use TOTP Validator?
Inputs are capped at 0 MB per file, which keeps memory usage stable across phones, tablets and older laptops. You can run TOTP Validator as often as you need; every run produces a full-quality result.
Does TOTP Validator work in Safari, Firefox, Chrome and Edge?
TOTP Validator 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.
Which file formats does TOTP Validator 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.
Does Favtoo keep a copy of files I process with TOTP Validator?
Favtoo keeps no copy of your file because Favtoo never receives your file. TOTP Validator 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.