Developer Utilities
Small developer utilities that save a trip to a random website. Encode and decode Base64, explain a regex, build UTM links, generate QR codes and vCards, and more — the everyday helpers. Free in your browser, and available by API when you need them in a script.
Parse dotenv file content into key-value pairs
Paste a .env file and get its settings as clean key–value pairs: in the sample, 7 keys come out, PORT keeps its later value 9090 and COLOR stays #336699…
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Check a path against .gitignore patterns
Find out whether Git would ignore a file and which rule decides: logs/build.log is ignored because of *.log, the second rule in the list, and a later rule such…
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Generate a TypeScript interface from JSON
Paste a sample object and get a ready TypeScript interface: in the example, id becomes number, tags becomes string[] and the key display-name is kept in quotes…
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Minify HTML code and measure the size reduction
Make a page lighter without changing what visitors see: the sample goes from 146 to 106 bytes, 27.4 % less, with 1 comment removed and its text, attributes…
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Minify JavaScript whitespace and measure the size reduction
Strip comments and spare spaces from JavaScript without renaming anything: the sample function add goes from 59 to 30 bytes, 49.15 % smaller, and line breaks…
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Check a Version Against a SemVer Range
Check whether a version fits a range in one step: 1.5.2 satisfies >=1.0.0 <2.0.0, while 1.5.0-beta.1 does not, because a broad range never lets an unstable…
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Explain a regex pattern in plain language
See what each piece of a regular expression does: the sample email pattern splits into 16 explained parts with 3 capture groups, the first named user, each with…
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Escape regex special characters for a literal match
Make any text safe to drop into a regular expression: invoice.total [draft]? becomes invoice\.total \[draft\]\?, so the period, brackets and question mark match…
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Bump a Semantic Version by Major, Minor, or Patch
Get the next release number without slips: a minor bump turns 2.7.4 into 2.8.0, resetting the patch to zero, and any prerelease or build suffix is dropped…
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Compare Semantic Version Numbers with SemVer Precedence
Find out which of two versions really comes first: 1.0.0-alpha.1 is lower than 1.0.0-alpha.beta, because a numeric label always ranks below a word, and 2.10.0…
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Build a parameterized SQL WHERE clause from filters
Turn search filters into a safe WHERE clause: status active, age of at least 21 and role admin or editor become quoted column names with numbered placeholders…
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Compute two's complement binary
Convert in both directions at a fixed width: -18 in 8 bits is 11101110, and reading 11101110 at 8 bits gives -18 again, with widths from 2 to 53 bits and no…
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YAML indentation and syntax checker with line numbers
Catch the structural slips that break a YAML file: in the sample, port repeated on line 4 after line 3 and a tab on line 5 give 2 findings, each with its line…
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Subnet usable host calculator
Know how many devices fit in an IPv4 subnet before you plan it: a /24, or 255.255.255.0, holds 256 addresses, of which 254 are usable hosts.
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Check WiFi channel overlap for 2.4 GHz channels
Find out whether two Wi-Fi channels step on each other: channel 1 sits at 2412 MHz and channel 6 at 2437 MHz, so their 20 MHz ranges do not overlap.
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Validate API key format
A key passes when it starts with the expected prefix, is exactly 18 characters long including that prefix and uses only letters and digits after it.
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CORS header configuration checker
A response that allows app.example.com with credentials and lists Origin in its Vary header passes with 0 issues.
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Check File Extension Risk Level for Email Attachments
Quarterly.Report.DOCM is read as .docm, a macro-capable document with high risk, so the advice is to quarantine it until a macro-aware scan clears it.
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Map data fields to GDPR categories and special-category flags
Out of five names, medicalHistory, union-membership and a face template are flagged as special categories (3), while a customer email and a preferred language…
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Compare hash algorithm output length and collision security
SHA-256 produces a 256-bit digest and its collision resistance is not broken, while MD5 and SHA-1 are flagged as broken.
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Build an HSTS header value
A lifetime of 31536000 seconds with both options on becomes one line: max-age first, then includeSubDomains, then preload.
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TOTP time window calculator
At Unix time 1700000000 with a 30-second period, you are in window 56666666 with 10 seconds left before the counter moves on.
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Classify data fields as PII
Five names give 2 direct identifiers, an email and a passport number, 2 indirect ones such as birthDate and device-id, and 1 non-personal order total, each with…
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Parse rate-limit response headers and calculate reset time
A limit of 100 with 42 remaining and a reset of 60 at 12:00 UTC means requests open again at 12:01, in 60 seconds.
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Estimate secure delete overwrite passes for SSD or HDD
On a modern hard disk, 1 complete overwrite pass is enough, while on an SSD no pass count is reliable, so a built-in sanitize or cryptographic erase is the…
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Format an SSH key fingerprint as colon hex or Base64
Hash bytes beginning 222, 173, 190 and 239 display as de:ad:be:ef in colon-separated hex, with a zero byte kept as 00, or as an unpadded Base64 string.
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Check whether a TLS version is still supported
Type a TLS version and see at once whether it is still supported: TLS 1.3 and TLS 1.2 pass, while TLS 1.0 and TLS 1.1 come back deprecated, each with a short…
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Seeded two-factor backup code generator
Ask for 5 recovery codes with a secret seed and you get 5 unique one-time codes such as 8476-8082, always the same list in the same order for that seed, so they…
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Webhook signature verification steps
Give the HMAC algorithm, such as HMAC-SHA256, and the header that carries the signature, and get 8 ordered steps: keep the raw body, rebuild the signed message…
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Convert text to the NATO phonetic alphabet
SOS becomes Sierra Oscar Sierra: paste a name, ticket reference or address and each English letter turns into its NATO radio word, in the same order.
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Seeded numeric PIN generator
Length 6 with the seed release-demo-2026 always gives 095015, and it is not flagged as weak. Build repeatable PINs for form tests, screenshots and demos, with…
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Validate feature flag names
Paste a flag name and see at once whether it follows the convention: enable-checkout-express passes, with the prefix enable and three lowercase segments.
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Extract GraphQL query variable names and types
Paste a GraphQL document and get its declared variables per operation: FindUser declares id as ID!, filters as [UserFilter!] and limit as Int, and Rename…
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Extract OpenAPI path parameters in template order
Pull the parameter names out of a path template in the exact order they appear: /users/{id}/posts/{postId} gives id, then postId.
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Shorten a Git commit hash to any valid length
Cut a full Git commit hash to exactly the length you choose: 8f14e45fceea167a5a36dedd4bea2543d2f6b721 at 12 characters becomes 8f14e45fceea, the same on every…
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Resolve configuration value precedence
Find out which configuration value really wins: with a default of development, a file saying staging and an environment variable saying production, the usual…
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Calculate a deterministic feature rollout percentage bucket
Enter a stable identifier and a rollout percentage to see whether that user is in: one sample user lands in bucket 81.41, so a 25% rollout leaves them out.
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Git branch naming convention validator
Give a branch name and your naming template: feature/ABC-123-add-login against type/ticket-description passes and splits into type feature, ticket ABC and…
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Idempotency key format check
Paste an idempotency key and see at once whether it is safe to send: order-7f3a9c2e-2026-07-25 passes, with 25 characters between the minimum of 16 and the…
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Rank log level severity order
Put log levels in their true order and compare any two: trace, debug, info, warn, error and fatal rise in severity, so warn against error comes out one step…
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Extract regex named capture groups
Paste a pattern such as (?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2}) and get its named groups in order: year, month and day.
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Diff package.json dependencies
Compare two dependency lists from package.json and see what really moved: react goes from ^17.0.2 to ^18.2.0, axios is added, moment is removed and lodash stays…
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Derive a URL slug from a Git branch name
Get a URL-friendly slug from a branch name: feature/add-user-login becomes add-user-login, with the workflow prefix left out and symbols turned into hyphens.
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Parse common log timestamp formats
Apache's 25/Jul/2026:14:30:00 +0200, syslog's Jul 25 14:30:00 and 2026-07-25T14:30:00.123Z each come back as one ISO 8601 UTC time, with epoch milliseconds and…
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Backup retention storage calculator with deduplication
Keeping 30 daily backups of 250 GB each needs 7,500 GB raw; with a 2.5:1 deduplication ratio that shrinks to 3,000 GB, or 3 TB, saving 4,500 GB.
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Log retention storage calculator
Turn daily log volume and a retention period into the storage you need: 250 GB a day kept for 30 days is 7,500 GB raw, and at a 0.4 compression ratio it shrinks…
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Build a Code 128 barcode payload and checksum
Check that a label value fits Code 128 Set B and get the symbol values a printer needs: KIT-128 starts with value 104 and its checksum value is 77.
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Convert Morse code to a timed light signal pattern
With a 100-millisecond unit, ... --- ... becomes 17 timed on and off steps: dots shine for 100 ms, dashes for 300 ms, and the whole distress signal lasts 2700…
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Build a vCard QR payload string
Ada Lovelace, her phone, email and company become one vCard 3.0 text that starts with BEGIN:VCARD and ends with END:VCARD, ready for any QR encoder.
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Build a WiFi QR payload string for WPA, WEP, or open networks
A network called Studio;WiFi is written as Studio\;WiFi inside the WiFi QR text, because a bare semicolon would cut the name short.
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Password entropy calculator
Sixteen random characters from lowercase, uppercase, digits and symbols (94 in all) give about 104.873 bits, and at 10 billion guesses per second an average…
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Explain Unix file permission octal
755 means the owner can read, write and execute, while the group and everyone else can read and execute, written rwxr-xr-x.
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Check Cookie Security Attributes
A session cookie set with Secure, HttpOnly and SameSite=Lax passes, because all three protections are present.
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SPDX license identifier lookup
Type an SPDX identifier and get the license behind it in plain words: Apache-2.0 is the Apache License 2.0, which allows commercial use, modification…
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Generate README badge Markdown with alt text
Get a README badge you can paste straight away from a label, a message and a color. Build and passing in bright green give complete Markdown with the alt text…
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Pagination offset and limit calculator
Convert the page a visitor picks into the values a database query expects: page 3 at 25 items per page starts at offset 50, and 123 items fill 5 pages.
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Resolve a slug collision with an incrementing numeric suffix
Keep a new page from replacing an old one: if report, report-2 and report-4 are taken, you get report-3, and a slug that is still available comes back…
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Validate an environment variable name
Check whether an environment variable name is portable before it breaks a deployment: DATABASE_URL passes, while a name that starts with a digit or contains a…
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Check password patterns
P@ssw0rd123 is flagged as medium risk because its swapped symbols still spell password. Check a password for keyboard runs, repeats and disguised common words…
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Bitwise NAND calculator
12 NAND 10 at 8 bits is 247, binary 11110111 and hex f7, after an intermediate AND of 8. Choose a width from 1 to 53 bits and see each step in decimal…
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