Free online developer tools
Formatters, decoders and file viewers for the text and files developers handle, from JSON and cron lines to SQLite databases and ISO 8583 messages. Apart from SQL Explainer and the generators, nothing you paste or open here is uploaded.
Format, validate and compare
Format and validate JSON, YAML, XML, TOML, SQL and nginx or Caddy configs, explain a query in plain English, and diff two files.
JSON Formatter & Validator
Format, validate, and beautify JSON with instant error detection. Free JSON formatter with live preview, minify mode, and syntax checking.
Free YAML Formatter
Pretty-print, compact, or validate YAML in the browser. A broken document shows the parser error. Free, no signup.
Free XML Formatter
Pretty-print or validate XML in the browser. A broken tag shows the parser error. Free, no signup.
Free TOML Editor
Parse, pretty-print, or validate TOML in the browser. A broken document shows the parser error. Free, no signup.
SQL Formatter
Format and standardize SQL with customizable indentation, keyword case, and line breaks. Free, no signup.
SQL Explainer
Translate SQL queries into plain English explanations. Breaks down SELECT, JOIN, WHERE, GROUP BY & more. Free, no sign-up.
Free nginx and Caddyfile Formatter
Re-indent nginx configs and Caddyfiles, explain each directive, and catch missing semicolons and braces. Free, no signup.
Free Diff Viewer
Compare two texts as a unified diff, side by side or word by word, and get a patch you can apply. Free, no signup.
Free .env File Diff
Compare two .env files key by key for missing, changed and duplicate variables, read the dotenv way. Free, no signup.
Encode, decode and hash
Convert Base64, URL escapes, HTML entities and Unicode, hash text with SHA-256, and decode JWTs, SAML responses, MessagePack, CBOR, protobuf and ASN.1.
Free Base64 Encoder and Decoder
Encode and decode standard or URL-safe Base64 in the browser. Invalid text shows an error. Free, no signup.
Free URL Encoder and Decoder
Encode a component or a full address without breaking query separators. Broken sequences show an error. Free, no signup.
Free Query String Editor
Split a URL query string into rows, convert it to JSON, or build an encoded query from plain lines. Free, no signup.
Free HTML Entity Encoder
Encode and decode named and numeric HTML entities in the browser. Unknown names show an error. Free, no signup.
Free Unicode Converter
Convert text to code points, UTF-8 bytes, escapes, and numeric character references, then back. Invalid scalars show an error.
Free Hash Generator
Compute SHA-1, SHA-256, SHA-384, and SHA-512 checksums in the browser. These digests check text. They do not store passwords.
Free JSON Web Token Decoder
Decode a JSON Web Token header and payload in the browser, and read the expiry. No signing and no secret cracking.
Free SAML Response Decoder
Decode SAMLResponse and SAMLRequest values from Base64, redirect URLs or XML, with timing and signature checks. Free, no signup.
Free MessagePack and CBOR Decoder
Decode MessagePack or CBOR bytes from hex or Base64 into JSON, with byte strings, tags and big integers kept exact. Free, no signup.
Free Protobuf Wire Decoder
Decode Protocol Buffers bytes without a .proto file: field numbers, wire types, nested messages and value readings. Free, no signup.
Free ASN.1 DER Decoder
Decode ASN.1 DER, BER or PEM into a tree with named OIDs, and check certificates, keys and CSRs against strict DER. Free, no signup.
Test patterns, queries and schedules
Try regex, JSONPath, JMESPath, XPath and CSS selectors, glob, CODEOWNERS and grok patterns, and see when a cron or systemd timer next runs.
Free Regular Expression Tester
Test a JavaScript regular expression with live matches, capture groups and replacements. Free, no signup.
Free JSONPath Tester
Run JSONPath against JSON and see every matched value or the exact path of each match, filters included. Free, no signup.
Free JMESPath Tester
Run JMESPath against JSON and see the result as JSON or AWS CLI text, with errors that name the bad token. Free, no signup.
Free XPath and CSS Selector Tester
Run a CSS selector or XPath against pasted HTML or XML with your browser’s engine and see every match. Free, no signup.
Free Glob and Gitignore Tester
Test paths against glob patterns or .gitignore rules and see which line matched, ignored or re-included each one. Free, no signup.
Free CODEOWNERS Tester
Check a GitHub CODEOWNERS file against paths: each file’s owners, the deciding line, and invalid owners. Free, no signup.
Free Grok Pattern Tester
Test grok patterns on log lines with the Logstash pattern library: fields, JSON events and the expanded regex. Free, no signup.
Free Cron Expression Tester
Read a cron expression in plain English and see its next five run times in UTC or your time zone. Free, no signup.
Free systemd OnCalendar Tester
See a systemd OnCalendar expression’s normalized form and next five elapse times, like systemd-analyze calendar. Free, no signup.
DevOps, logs and security
Draw Docker Compose and GitHub Actions graphs, review IAM policies and CSP headers, score CVSS, and read access logs, traces, HAR files and stack traces.
Free Docker Compose Visualizer
Draw a docker-compose.yml’s services and depends_on links, and catch missing services and cycles. Free, no signup.
Free GitHub Actions Workflow Visualizer
Draw a workflow’s triggers, jobs and needs, and flag unknown needs, cycles and jobs missing runs-on. Free, no signup.
Free AWS IAM Policy Explainer
Read an AWS IAM policy in plain language and flag admin access, broad iam:PassRole and public principals. Free, no signup.
Free CSP Evaluator and Builder
Find unsafe-inline, wildcards, missing object-src and typos in a Content-Security-Policy, then export it. Free, no signup.
Free CVSS Calculator
Score CVSS 4.0, 3.1, 3.0 and 2.0 vectors with severity, every metric explained and the CVSS JSON record. Free, no signup.
Free Access Log Analyzer
Summarise nginx and Apache access logs by status, path and client, and list every 4xx and 5xx by line. Free, no signup.
Free logfmt Parser
Turn logfmt key=value log lines into a table or JSON, with level counts and the lines that didn’t parse. Free, no signup.
Free OpenTelemetry Trace Viewer
View OTLP, Jaeger or Zipkin trace JSON as a span waterfall, with self time and failed spans. Free, no signup.
Free Stack Trace Resolver
Apply a source map to a minified JavaScript stack trace and see original files, lines and source lines. Free, no signup.
Free HAR File Viewer
See a HAR file’s request waterfall, page timings and failures, find cookies and tokens, and save a redacted copy. Free, no signup.
Free ANSI Escape Code Previewer
Preview terminal ANSI colour codes, strip them to plain text, or list every SGR code a log uses. Free, no signup.
Data files
Open SQLite, Parquet, Avro, Arrow and CSV files, check data against a JSON Schema, and inspect PO and XLIFF translations, .ics calendars and .vcf contacts.
Free SQLite Viewer
Open SQLite .db files to browse tables and columns, run SQL with CSV results, and read the file header. Free, no signup.
Free Parquet Viewer
See a Parquet file’s schema, row groups, compression and column statistics, then query it with DuckDB. Free, no signup.
Free Avro and Arrow Viewer
Read Avro and Arrow files as JSON records, see their schema, and check codec, blocks and metadata. Free, no signup.
Free CSV Editor
View a CSV as a table, find the row that breaks it, and convert between comma, semicolon and tab. Free, no signup.
Free JSON Schema Form Preview
List the form fields a JSON Schema defines and validate JSON data against it, for drafts 2020-12 to draft-06. Free, no signup.
Free PO and XLIFF Editor
Check gettext PO files and XLIFF 1.2 or 2.0: coverage, fuzzy and missing entries, and dropped placeholders. Free, no signup.
Free iCalendar Viewer
Open .ics calendars as an agenda, expand recurring events, and check UIDs, zones and times. Free, no signup.
Free vCard Previewer
Open .vcf contact files as cards, list every field, and check vCard 2.1, 3.0 and 4.0 files. Free, no signup.
Trace a message through its Received headers, read SPF, DKIM and DMARC records, and open .eml, Outlook .msg and .mbox files.
Free Email Header Analyzer
Read SPF, DKIM and DMARC results, trace each server hop with delays, and spot phishing signs in headers. Free, no signup.
Free SPF, DKIM and DMARC Explainer
Read SPF, DKIM and DMARC records term by term and catch too many lookups, +all, weak keys and p=none. Free, no signup.
Free EML and MSG Viewer
Open .eml and Outlook .msg files to read the message, attachments and MIME parts, with tracking images blocked. Free, no signup.
Free MBOX Viewer
List the messages in an mbox file from Gmail Takeout or Thunderbird, rank senders, and export to CSV. Free, no signup.
Docs and diagrams
Preview Markdown, AsciiDoc, Typst and forum BBCode as you type, and draw flowcharts, sequence diagrams and Gantt charts in Mermaid.
Markdown Previewer
Live markdown editor with real-time preview, formatting toolbar, and GitHub Flavored Markdown support. Edit left, see rendered right.
Free AsciiDoc Previewer
Render AsciiDoc with Asciidoctor, copy the HTML, and outline sections, images and warnings. Free, no signup.
Free Mermaid Diagram Editor
Render Mermaid diagrams as you type, export the SVG, and check for missing accessibility text. Free, no signup.
Free Typst Previewer
Compile Typst in your browser, read compiler errors in plain words, and outline headings and labels. Free, no signup.
Free BBCode Editor
Preview forum BBCode, copy the HTML or Markdown, and find unclosed tags and unsafe links. Free, no signup.
Payment, health and trade messages
Parse ISO 8583, EMV, ISO 20022, SWIFT MT and FIX messages, HL7 v2 records, X12 and EDIFACT documents, and GS1 barcode data.
Free ISO 8583 Parser
Parse ISO 8583 card messages in BCD or ASCII: MTI, bitmaps, all 128 fields and EMV field 55, card data masked. Free, no signup.
Free EMV TLV Decoder
Decode EMV TLV from cards and ISO 8583 field 55: tags named, TVR, TSI and AIP bits explained, card data masked. Free, no signup.
Free ISO 20022 Parser
Read pain, pacs and camt payment XML as plain lines, with NbOfTxs, CtrlSum and IBAN check digits verified. Free, no signup.
Free SWIFT MT Parser
Parse SWIFT MT103, MT202 and MT940 messages: headers, UETR and every field, with balances and IBANs checked. Free, no signup.
Free FIX Message Parser
Parse FIX 4.x and 5.0 messages from logs with every tag named, and BodyLength and CheckSum recomputed over SOH. Free, no signup.
Free HL7 v2 Message Viewer
Read HL7 v2 messages field by field with codes explained, and a de-identified view that masks patient data. Free, no signup.
Free EDI X12 Viewer
View X12 EDI files segment by segment, with delimiters read from ISA and envelope counts and control numbers checked. Free, no signup.
Free EDIFACT Viewer
View UN/EDIFACT interchanges segment by segment, with UNA delimiters, qualifiers explained and UNT and UNZ checked. Free, no signup.
Free GS1 Barcode Parser
Parse GS1 barcode data, verify GTIN, SSCC and GLN check digits, decode dates and weights, and convert to Digital Link. Free, no signup.
Vehicles, chargers and machines
Decode CAN frames with a DBC file, read J1939 and OBD-II data and charging station messages in OCPP or OCPI, and preview G-code in 3D.
Free CAN DBC Viewer
Open a Vector .dbc file to list CAN messages and signals with scaling, byte order and a bit layout per message. Free, no signup.
Free CAN Frame Decoder
Decode candump and cansend CAN frames into signal values with units using your DBC file, multiplexing included. Free, no signup.
Free J1939 PGN Decoder
Decode J1939 frames into PGNs, SPN values with units, DM1 fault codes and address claims, no DBC needed. Free, no signup.
Free OBD-II PID Decoder
Turn ELM327 and OBD-II responses into values with units, trouble codes and the VIN, with each J1979 formula. Free, no signup.
Free OCPP Message Validator
Check OCPP 1.6 and 2.0.1 frames from EV charger logs against the protocol schemas, with problems listed by field. Free, no signup.
Free OCPI Message Viewer
Read OCPI 2.2.1 locations, sessions, CDRs, tariffs and tokens as plain lines, with schema checks and a map. Free, no signup.
Free G-code Viewer
See 3D-printer and CNC G-code in 3D with layers, filament, temperatures, size and run time. Free, no signup.
Maps, aviation and shipping
Put GPX tracks, GeoJSON and encoded polylines on a map, and decode NMEA and AIS sentences, METAR and TAF weather reports and NOTAMs.
Free GPX Viewer
See a GPX track on a map with distance, moving time, pace, elevation, heart rate and per-km splits. Free, no signup.
Free GeoJSON Viewer and Validator
Map GeoJSON, WKT or KML, check it against RFC 7946, and convert between GeoJSON and WKT. Free, no signup.
Free Polyline Decoder
Decode Google encoded polylines and polyline6 onto a map, export GeoJSON, or encode coordinates. Free, no signup.
Free NMEA Sentence Decoder
Decode NMEA 0183 GPS and marine sentences, check every checksum, map the track and export GeoJSON. Free, no signup.
Free AIS Message Decoder
Decode AIS !AIVDM sentences into vessel positions, names, types and voyages, with multi-part messages joined. Free, no signup.
Free METAR and TAF Decoder
Translate METAR and TAF reports into plain language, with change periods, US remarks and flight category. Free, no signup.
Free NOTAM Decoder
Decode ICAO and FAA NOTAMs: Q codes, times, limits and areas, with abbreviations written in full. Free, no signup.
IDs, test data and schemas
Generate GUIDs, random strings and valid IMEI and ISBN numbers, and turn a plain-language decision into a Jev JSON schema.
Online GUID Generator
Generate real, RFC 4122-compliant GUIDs and UUIDs (v1, v3, v4, v5, v7). Bulk up to 100, lowercase or uppercase, with or without hyphens. Free.
AI Random String Generator
Generate random strings with AI. Choose alphanumeric, hex, UUID, or custom formats. Set length and case. Free online string generator tool.
Random IMEI Generator
Generate valid random IMEI numbers with Luhn checksum verification. Choose from 10 device manufacturers, set batch size. Free online IMEI number generator.
Free ISBN Generator
Generate valid ISBN-13 and ISBN-10 numbers in bulk with correct check digits. Hyphenated or compact, up to 100 per click. Free, no signup.
Jev Question Builder
Transform plain-language decisions into valid Jev JSON schemas. Build Choice, Score, and Noul questions for routing, classification, and guardrails. Free, no signup.
Propose a tool
Tell us what it should do. We build the most requested ones.
Showing 85 of 85
Start from the file or text you have
A SQLite database from an app or a phone backup
Open it in the SQLite Viewer to list its tables and columns, run SQL against it and save the results as CSV.
A Parquet export from a data pipeline
The Parquet Viewer shows its schema, row groups, compression and column statistics, then lets you query it with SQL in DuckDB.
A token from an Authorization header
The JSON Web Token Decoder shows the header and claims, turns exp, nbf and iat into dates, and flags unsigned alg none tokens.
The raw headers of a suspicious email
The Email Header Analyzer lists every server hop with its delay and TLS, shows the SPF, DKIM and DMARC results, and points out a mismatched Reply-To.
A HAR export from the browser’s Network panel
The HAR File Viewer draws the request waterfall, lists failed and slow requests, and saves a redacted copy you can share.
An ISO 8583 message from a payment switch log
The ISO 8583 Parser names the MTI, bitmaps and all 128 fields, decodes amounts, response codes and field 55, and masks card numbers.
CAN frames and the DBC file that describes them
Paste both into the CAN Frame Decoder to turn raw bytes into signal values with units, including multiplexed and extended frames.
A minified stack trace from production
Give the Stack Trace Resolver the trace and the bundle’s source map to get the original file, line and column of each frame.
A GPX file from Garmin, Strava or Komoot
The GPX Viewer maps the route and works out distance, moving time, pace, climbing and per-kilometre splits. Map tiles load from OpenStreetMap.
A cron line from a crontab or CI config
The Cron Expression Builder reads it in plain English and lists the next five run times in UTC or your time zone.