Validators, testers and debuggers
Paste the thing that broke and find out where. Every check runs in your browser on text you bring, points at a line and column, and says which parts of the spec it actually verified.
JSON Repair Tool
Paste JSON that will not parse and get it back working, with every repair listed at the line and column it happened.
JSON Schema Validator With Human Errors
Check a document against a JSON Schema and get errors that name the value, the expectation and the line — plus the list of keywords in your schema that were not checked.
Streaming JSON Parser Demo
Drag a slider through a JSON document byte by byte and watch which fields are safe to render and which are still being written.
SSE Stream Inspector
Paste a raw server-sent event stream and see the events a compliant client would actually dispatch, plus the framing mistakes that silently drop one.
Prompt Linter
Checks a prompt for contradictions, unverifiable wording, dead references and template variables that will never be substituted.
Prompt Injection Tester
Audit whether your architecture makes prompt injection matter, check your system prompt's structure, and generate a canary-scored test suite to run against your own endpoint.
Jailbreak Resistance Checklist
Twenty-four structural questions about threat model, input handling, output handling, blast radius, monitoring and evaluation, scored by category.
PII Detector
Find personal identifiers in pasted text, with card numbers and IBANs verified against their real check digits and every detector labelled by what its check actually is.
Secret Scanner for Prompts
Catch API keys, tokens, private keys and connection strings in text before you paste it into a chat window, a ticket or a prompt.
Text Redactor
Replace identifiers with stable placeholders before sending text to a model, then put the originals back when the answer returns.
Output Diff Viewer
Compare two model outputs word by word, choosing what should not count as a difference, and see how much of the change your normalisation absorbed.
Regex Tester With Backtracking Warning
Test a pattern against your own text with a step budget, and find out before production whether it can be made to backtrack catastrophically.
Unicode Inspector
Find the zero-width spaces, direction overrides, look-alike letters and stray control characters that make two identical-looking strings compare unequal.
Encoding Detector and Fixer
Repair text mangled by a wrong decoder, in as many rounds as it took to break it, and see the exact position where the damage starts.
Webhook Signature Verifier
Check an HMAC webhook signature against your own payload and secret, and find out which detail is wrong when it does not match.
JWT Inspector
Decode a JWT, read every claim with what it is for, and check the time claims against your clock — with nothing sent anywhere.
API Response Inspector
Paste a completion response and get every field explained, plus the arithmetic checks that catch a truncated or malformed one.
Error Code Lookup
Paste an error body, a status line or a stack trace and get the likely cause, whether it is retryable, and what to change.
Latency Percentile Calculator
Paste your timings for p50 through p99.9, a histogram, a breach rate against your target, and an interval on every headline figure.
Statistical Significance Calculator for Evals
Decide whether one variant really beat another on a small, noisy eval set, using exact tests rather than large-sample approximations.
Sample Size Calculator for Evals
Work out how many examples an eval set needs before a difference between two prompts or two models means anything.
Inter-Rater Agreement Calculator
Paste two columns of labels and get Cohen's kappa, weighted kappa, the confusion matrix and the reason your raters disagree.
Confusion Matrix Explorer
Paste predictions or type four counts, and get the matrix with every metric derived from it — each one defined next to its value.
Threshold Tuner
Drag a threshold across your own scores and watch precision, recall and expected cost move with it.
Calibration Plot Builder
Paste confidence scores and outcomes to see whether 80% confident really means right eight times in ten.
Text Similarity Checker
Compare two texts with five lexical similarity metrics, computed exactly in your browser, with the words each one has and the other lacks.
Duplicate Detection Threshold Finder
Paste your own items and sweep the similarity cutoff until the pairs it merges stop looking like duplicates.
Chunking Quality Inspector
Run five splitters over your own text and see the line, column and surrounding characters of every cut, plus what each one broke.
Retrieval Debugger
Paste a query and your chunks to see a BM25 ranking broken down term by term, including the query terms that appear nowhere at all.
AI Feature Launch Checklist
Thirty things to settle before an AI feature ships, each with the reason it is cheap now and expensive later, exportable as markdown.