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All developer tools
Every tool on HeyUtils in one list, grouped by topic and category. Filter by name or format, or jump to a group.
306 tools in 41 categories
306 of 306 tools
Data & Formats
Format, validate, convert and query structured data: JSON, YAML, TOML, XML, CSV, schemas and binary files.
JSON 23 tools
- JSON formatter Format JSON with exact numbers while keeping large IDs and decimals intact
- JSON validator Validate JSON syntax and find duplicate-key warnings with error positions
- JSON repair Propose JSON fixes with highlighted changes and individual acceptance
- Large JSON viewer Browse large JSON files in chunks without uploading or freezing
- CSV to JSON Converter Convert CSV and TSV to JSON with header and type handling
- JSON to CSV Convert JSON arrays to CSV with explicit column selection and header control
- JSON to YAML Transform JSON to YAML preserving exact number types and indentation style
- YAML to JSON Convert YAML to JSON preserving root type and controlling anchor expansion
- JSON to TOML Transform JSON objects to TOML sections with table and array-of-tables syntax
- TOML to JSON Parse TOML to JSON preserving dates as strings and handling unsafe integers
- JSON to XML Map JSON to XML with custom roots, attributes and array element naming
- XML to JSON Map XML to JSON with configurable attribute handling and array detection
- JSON to Markdown table Generate Markdown tables from JSON with custom columns and field reordering
- JSON diff Compare API responses and configs to find actual data changes
- JSON merge Combine JSON with explicit precedence rules and inspect conflicts before exporting
- JSON flatten Turn nested JSON into typed paths or restore it from flat keys
- JSON key extractor List keys, select fields and convert JSON entries with deduplication
- JSONPath tester Find values and their paths in nested JSON using JSONPath query syntax
- JMESPath tester Filter and reshape JSON using JMESPath expressions with live results
- jq playground Run real jq 1.8.2 on JSON or text, inspect stdout and exit codes, then copy the command
- JSON Pointer Locate exact values using RFC addresses and parse the paths they contain
Schema & Type Generation 11 tools
- JSON to TypeScript Generate TypeScript types from multiple array samples with field analysis
- JSON to Go Generate Go structs from all array samples with json tags and nil pointers
- JSON to Java Generate Jackson models from JSON samples with nullable field detection
- JSON to Python Build dataclass or Pydantic models from representative API responses
- JSON to Swift Create Swift Codable structs from API examples with optional field inference
- JSON to model Generate Rust, C#, Dart, PHP and Scala types from JSON samples
- JSON Schema generator Infer JSON Schema from multiple samples with optional field detection
- JSON Schema validator Check instances against schemas and report rule violations with paths
- JSON Schema diff Compare schemas and flag breaking changes by data direction
- JSON Schema Mock Data Generator Generate seeded JSON fixtures from JSON Schema with reproducible results
YAML / TOML / ENV Config 15 tools
- YAML formatter Reformat YAML while preserving comments, anchors and exact numbers
- YAML diff Compare YAML documents by structure while preserving original comments
- YAML anchor explorer Trace YAML anchor references and expand aliases with cycle detection
- TOML formatter Format TOML files while preserving comments and configuration structure
- .env editor Review and edit environment variables in a table with duplicate detection
- ENV Diff & Missing Keys Compare .env files by key to find missing variables and changed values
- .env example generator Create .env templates by clearing values and selectively preserving keys
- ENV to JSON Convert ENV files to JSON with explicit type preservation
- Config converter Convert between INI, Properties and plist configuration formats
- Config diff Compare TOML, INI and Properties files ignoring key order
XML / XPath / XSD 10 tools
- XML formatter Beautify XML and inspect structure while keeping text nodes intact
- XML escape Escape or unescape text content and attribute values for XML contexts
- XML to CSV converter Extract records from XML and export as CSV with path selection
- XPath tester Query XML documents with XPath 1.0 and bind namespace prefixes
- XQuery tester Run XQuery 3.1 FLWOR queries and constructors against XML
- XSD validator Validate XML against XSD 1.0 schemas with local file resolution
- XML to XSD generator Generate XSD 1.0 from XML samples to identify optional fields
- XSD to JSON Schema Map XSD elements and types to JSON Schema with approximation warnings
CSV / TSV Tabular Data 10 tools
- CSV / TSV editor Edit CSV cells individually, preserving leading zeros and cell values
- CSV cleaner Remove duplicates, filter rows and reorder columns with step preview
- CSV transpose Swap CSV rows and columns with header and padding preview
- CSV delimiter converter Change CSV delimiters from comma to tab, semicolon or custom
- CSV to Markdown Convert CSV to Markdown table with column selection and alignment
- CSV join Join two CSV files by key or append records by matching column names
- Split CSV files Split large CSV files by record count, size or column value
Files, Binary & Compression 8 tools
- Hex Viewer Browse any file as offset, hex and ASCII columns with byte search
- File Type Checker Identify file format from magic bytes and flag extension mismatches
- Executable file inspector Read ELF, PE and Mach-O executable headers and sections
- Compare Binary Files Compare binary files byte by byte to find exact offsets of changes
- Source Map Viewer Decode minified stack traces back to original source files and lines
- File to Base64 Encode files to Base64 or data: URLs and restore original bytes
- File checksum Calculate MD5, SHA-1, SHA-256 and other checksums for downloaded files
- Gzip / Deflate / Brotli Compression Tool Compress or decompress with real Gzip, Deflate and Brotli, capped for safe decompression
Text & Encoding
Clean up and compare text, test regular expressions, encode or escape strings, inspect Unicode and generate IDs.
Text & Strings 8 tools
- Whitespace cleaner Remove trailing spaces, collapse blanks and convert tabs with visual feedback
- Text line tools Chain trim, dedupe, sort, filter, number and join steps on a list, reordering to preview results
- Line ending converter Normalize CRLF, LF and CR across files with encoding preservation
- Pattern extractor Extract emails, URLs, IPs or regex matches and deduplicate results
- Case converter Transform text between naming styles like camelCase, snake_case and more
- text diff Compare lines, words or characters and export exact unified patch format
- Word counter Measure Unicode units, bytes, words and lines with frequency distribution
- Lorem Ipsum generator Create reproducible filler text with seeded content and multiple formats
Regex & Pattern Matching 7 tools
- URL pattern tester Test URLPattern and path-to-regexp routes with capture inspection
- Gitignore tester Trace which gitignore rules match paths and explain decision chains
- Glob tester Check glob patterns against paths using minimatch or picomatch engines
- Regex tester Test JavaScript regex with visible captures and group replacements
- Python regex tester Run patterns through actual CPython re, inspecting named groups, Unicode spans and flags
- Regex flavor tester Compare PCRE2 and RE2 regex implementations on real expressions
Encoding & Escaping 9 tools
- Base64 encoder Convert between text and Base64 with strict UTF-8 and alphabet options
- Base encoding converter Encode and decode Base16, Base32, Base58, Base85 with alphabet selection
- Text & binary / Hex Encode or decode text to binary, hex or bytes with explicit character encoding
- URL encoder Encode or decode URL components, full URIs and form field values
- HTML entity encoder Convert between HTML text and named or numeric entity references
- String escape Escape or unescape strings for JSON, JavaScript and Unicode contexts
- Data URI converter Generate or decode data: URLs for embedded resources in CSS and HTML
- Punycode converter Transform between Unicode and ASCII domain names side by side
- ROT13 / ROT47 & Morse Apply ROT13, ROT47, Caesar shifts or Morse encoding with live results
UUID / ID Generators 8 tools
- UUID generator Generate UUIDs v1, v3, v4, v5, v6 and v7 or create repeatable names
- UUID decoder Inspect UUID versions, variants and timestamps from identifier strings
- ULID generator Generate monotonic ULIDs and decode embedded timestamps from IDs
- Snowflake ID decoder Extract timestamps and node IDs from Snowflake format identifiers
- ObjectId generator Generate or decode MongoDB ObjectIds with embedded timestamp extraction
- Modern ID generator Generate Nano ID, CUID, CUID2 and KSUID with custom alphabets
- Random string generator Generate passwords, integers, bytes and test IPs with seed control
Unicode & i18n 9 tools
- Unicode inspector Inspect code points, graphemes and UTF-8 bytes behind character sequences
- invisible character detector Reveal hidden Unicode and zero-width characters in pasted text
- Unicode confusable detector Identify lookalike characters from different scripts and check similarity
- Unicode normalizer Compare NFC, NFD, NFKC and NFKD normalization forms visually
- Mojibake fixer Fix mojibake by selecting among repair candidates with byte inspection
- BCP 47 language tag parser Parse BCP 47 language tags and Accept-Language header q-values
- ICU MessageFormat tester Test ICU MessageFormat with plurals and select branches across boundaries
Time & Math
Convert timestamps and time zones, build cron schedules, and work with number bases, bits and units.
Date & Timestamps 13 tools
- Unix timestamp converter Convert between Unix timestamps and dates across units and timezones
- ISO 8601 / RFC date parser Parse ISO 8601 and RFC dates with exact offset handling and batch support
- Time zone converter Compare local times across multiple IANA zones on specific dates
- Date calculator Calculate intervals, workdays and anniversaries with explicit day counting rules
- duration converter Convert between ISO 8601, clock notation and decimal duration units
- .NET ticks converter Decode .NET DateTime.Ticks with 100 nanosecond precision preservation
- Excel serial date converter Convert Excel serial dates to UTC dates with workbook system selection
- FILETIME converter Read Windows FILETIME and LDAP timestamps with 100 nanosecond accuracy
- WebKit timestamp converter Decode Chrome database microsecond timestamps to UTC dates
Cron & Scheduling 6 tools
- Jenkins cron generator Build Jenkins cron expressions and explain H hash distribution ranges
- Cron expression generator Design five-field cron schedules with timezone context and run previews
- systemd Timer Generator Generate systemd timer units for calendar and boot-relative triggers
- AWS EventBridge cron Compose EventBridge cron and rate expressions with timezone handling
- Quartz cron generator Build Quartz six-field cron with L, W and # special rules and previews
- RRULE generator Create RRULE recurrence patterns and preview matching dates
Numbers, Bitwise & Units 7 tools
- transfer time calculator Estimate download duration from size and bandwidth or find needed speed
- Data size converter Convert between bits, bytes, KB, MB, GB and binary units
- Number base converter Convert integers between bases 2–36 without rounding large numbers
- bitwise calculator Perform AND, OR, XOR, NOT and shift operations on 8–64 bit values
- two's complement calculator Read 64-bit words as signed or unsigned with two's complement
- IEEE 754 converter See the exact decimal value behind 32 and 64-bit floating point bits
API & Security
Debug HTTP requests and APIs, parse URLs, decode JWTs, build security headers and generate hashes and keys.
Hash & Crypto Helpers 9 tools
- Hash generator Compare multiple hash algorithms with configurable salt positions
- HMAC generator Generate and verify HMAC-SHA digests with message and key encoding
- Password hash generator Generate and verify salted hashes with bcrypt, scrypt, Argon2id or PBKDF2
- CRC calculator Compute CRC16, CRC32 or Adler-32 checksums with model parameter selection
- Key pair generator Generate an RSA or EC test key pair, or inspect an existing key, then export as PEM or JWK
- SSH key inspector Read OpenSSH public key algorithms and compute SHA256 fingerprints
- AES-GCM encrypt/decrypt test Encrypt and decrypt with AES-GCM using raw keys and nonce separation
URL / URI Tools 7 tools
- URI template tester Expand RFC 6570 URI templates and inspect each expression encoding
- URL parser Break down URLs into components and reveal how the runtime normalizes each one
- URL normalizer & joiner Normalize URLs, resolve relative paths and control percent encoding
- UTM link builder Create campaign links with explicit merge rules from CSV batches
- Query string builder Build URL parameters preserving repeated keys and empty values
HTTP & Request Debugging 12 tools
- HTTP headers parser Inspect HTTP request and response headers with duplicate preservation
- Cache-Control generator Build Cache-Control response headers and compare cache lifetimes
- User Agent Parser Parse OS, device and rendering-engine fields from batch User-Agent header lines
- Online HTTP client Send a single HTTP request to any API and inspect its status, headers and body directly
- Online HTTP header checker Check response headers from a public URL for caching and security
- redirect checker Trace HTTP redirect chains to see every hop before the destination
- CORS tester Validate CORS headers against Origin and request method
- Webhook tester Receive HTTP callbacks at a temporary URL to inspect webhook payloads
- cURL converter Generate Fetch, Axios and Python from curl commands or JavaScript
OpenAPI / GraphQL / Postman 7 tools
- Postman to OpenAPI Convert Postman collections to OpenAPI with request inspection
- OpenAPI editor Edit Swagger 2.0 and OpenAPI 3.x specifications with validation
- OpenAPI diff Compare two API specifications to review changes and breaking risks
- OpenAPI mock generator Generate request and response JSON fixtures from API operations
- GraphQL workbench Format GraphQL queries, SDL and variables with optional schema validation
- GraphQL schema diff Compare GraphQL schemas to identify type, field and argument changes
JWT / OAuth / Auth 7 tools
- JWT debugger Decode JWT claims as UTC dates and verify signatures with explicit keys
- JWK converter Convert JWKS sets and PEM keys to JWK format with thumbprint validation
- PKCE generator Generate PKCE verifier and S256 challenge pairs for OAuth
- OAuth / OIDC URL builder Assemble OAuth authorization requests with PKCE and inspect callbacks
- Authentication header helper Generate Basic Auth headers and inspect Bearer token structure
- OIDC Discovery viewer & validator Validate OIDC discovery documents and compare endpoint configurations
Web Security Config 5 tools
- SRI hash generator Generate SRI integrity hashes for script and stylesheet integrity attributes
- Cookie parser Inspect Cookie request and Set-Cookie response headers separately
- Security Headers Generator Draft CORS, CSP, HSTS and other security response headers
- CSP generator Design CSP headers and test resource matching without site requests
Network & Certificates
Look up DNS records, calculate subnets, inspect TLS certificates and check email authentication records.
DNS & Domains 5 tools
- DNS zone editor Parse BIND zone files and build DNS records with TTL and context
- DNS lookup Query DNS record types like A, MX, TXT, CNAME and SOA via Cloudflare or Google resolvers
- Reverse DNS name generator Build PTR names for IPv4/IPv6 addresses and aligned CIDR zones
- Domain & hostname validator Check hostnames, IDN labels and FQDNs against syntax and length rules
IP & Subnet Tools 8 tools
- Subnet calculator Determine network boundaries and host counts with CIDR and netmask support
- CIDR set calculator Merge, split, intersect or exclude IPv4 and IPv6 networks
- IP range to CIDR Convert inclusive IP ranges to minimal CIDR blocks without address loss
- IP converter Convert IPv4 and IPv6 between decimal, hex, binary and standard notation
- MAC address formatter Convert MAC addresses between colon, hyphen, Cisco and hex notation
- TCP flag decoder Interpret TCP control bits from decimal, hex or binary values
- ASN lookup Identify IP addresses and AS numbers using public BGP data
- Network connectivity test Run remote ICMP, TCP or traceroute probes from a different region
SSL / TLS Certificates 8 tools
- certificate decoder Extract SANs, extensions and expiry from PEM and DER certificates
- Certificate converter Convert certificates between PEM and DER formats with chain splitting
- CSR decoder and generator Inspect certificate signing requests and generate test CSRs with keys
- Certificate chain checker Verify PEM certificate chains and find missing issuers in bundles
- certificate hostname matcher Check if hostnames match certificate SAN lists with matching reasons
- SSL Certificate Checker Check live TLS certificates from public hosts and examine expiry dates
Email Dev Tools 6 tools
- DMARC record builder and parser Build or parse DMARC records, then review alignment and policy choices
- DKIM / BIMI record helper Inspect DKIM TXT records and draft BIMI values without DNS queries
- Email DNS checker Query live MX, SPF, DMARC and DKIM records for email domains
- Email address and mailto builder Build mailto links with recipients, subject and body encoding
- EML / MIME local viewer Read EML MIME messages and inspect decoded headers without a mail client
- SPF record builder and static checker Generate SPF TXT records from ordered sender rules with policy warnings
Dev & Ops
Work with SQL and databases, Git, package versions, Linux, Docker, Kubernetes, cloud resources, CI/CD and logs.
Database & SQL 10 tools
- SQL formatter Format SQL for five dialects with indentation and keyword case control
- SQL schema visualizer Visualize MySQL, PostgreSQL and SQLite schemas as a relationship graph
- SQL INSERT converter Extract rows from SQL INSERT statements into JSON or CSV
- JSON to SQL Convert JSON or CSV into SQL INSERT statements for a target table
- DynamoDB JSON converter Convert between DynamoDB JSON format and plain JSON with type preservation
- MongoDB Extended JSON Converter Transform MongoDB EJSON between Canonical and Relaxed formats
- PostgreSQL array parser Parse PostgreSQL arrays, intervals and dimensions with JSON export
- SQLite viewer Browse SQLite database tables and run read-only SELECT queries
- Database URL parser Extract host, port, credentials and database from connection strings
Git & Version Control 9 tools
- Git command builder Build common Git commands with explanations and risk warnings
- Git simulator Preview merge, rebase or cherry-pick effects on a sample commit graph
- Git diff viewer Read unified patch files side by side with hunk navigation
- Conventional Commit Builder Compose and validate commit messages with types, scopes and footers
- Git branch name validator Check branch names, references and object IDs for syntax errors
- Gitignore generator Combine language, OS and editor templates, then review before downloading
- GitHub URL converter Parse GitHub repository links and switch between Blob and Raw formats
Versioning & Packages 8 tools
- Semver calculator Compare versions, test npm ranges and calculate next release increments
- PEP 440 version checker Normalize and sort Python versions with PEP 440 constraint checking
- Package version tools Test version ranges for Composer, NuGet, Go and Cargo without querying any registry
- package.json editor Validate package.json manifest, check field errors and sort dependencies
- package.json exports visualizer Test subpath exports against import and require resolution
- Browserslist query Resolve Browserslist queries and compare two target version sets side by side
- Maven to Gradle converter Convert dependency declarations between Maven XML and Gradle DSL
- Python dependency file tools Parse requirements.txt and pyproject.toml with constraint inspection
Linux & Shell 5 tools
- Command Line and PATH Parser Parse POSIX command syntax, PATH order and environment keys
- Linux capability decoder Decode Linux capability hex masks to readable names and bits
- Shell escape Quote arguments for POSIX, Bash and PowerShell without shell interpretation
- Chmod calculator Convert between rwx symbols and octal modes with special bit explanation
- umask calculator Compare file and directory permissions affected by umask masks
Docker & Containers 4 tools
- Docker Compose workbench Review Compose YAML with port conflicts and dependency diagnostics
- Docker image parser Parse Docker image references to see registry, repository, tag and digest
- Docker Run builder Compose a docker run command with ports, mounts and environment variables
- Dockerfile editor Inspect multi-stage Dockerfile with line diagnostics and formatting
Kubernetes & Helm 9 tools
- Kubernetes YAML validator Validate YAML manifests against Kubernetes schemas with field diagnostics
- Kubernetes YAML generator Generate Deployment, Service, Ingress and probe YAML fragments
- Kubernetes resource calculator Convert CPU, memory and Quantity values or total container requests
- Helm Values Diff Show the effect of Helm value overrides against chart defaults
- Kubernetes label selector Test label selectors against JSON labels with match reasons
- Service / Ingress routing tester Trace Ingress paths through Service ports and targetPort references
- ConfigMap / Secret / ENV Convert dotenv and text files into ConfigMap and Secret manifests
- Kubernetes RBAC viewer Trace RBAC bindings through roles to see granted permissions
Cloud Dev Helpers 9 tools
- AWS ARN Parser & Builder Parse AWS ARN identifiers in bulk or assemble them from five fields
- AWS SigV4 Debugger Build AWS SigV4 canonical requests to diagnose signature mismatches
- S3 URL converter Parse S3 addresses and convert between path and virtual-hosted formats
- IAM policy viewer Extract and group IAM policy statements with actions and resources
- CloudFormation template validator Check CloudFormation templates for syntax and reference errors
- Azure resource parser Parse Azure resource IDs, storage URLs and connection strings
- GCP resources & GCS URLs Inspect GCP resource paths, GCS URLs and service account JSON
CI/CD 6 tools
- GitHub Actions Workflow Validator Validate GitHub Actions workflows and draft matrix or cron expressions
- GitHub Actions expression tester Evaluate conditions with mock GitHub Actions context variables
- GitLab CI editor Format and validate .gitlab-ci.yml with rule and include checking
- Semantic Release Calculator Calculate semantic version bumps and changelog from conventional commits
Logs & Observability 8 tools
- Access Log Parser Parse Nginx and Apache access logs with custom format support
- AWS Log Parser Analyze CloudFront and ALB access logs with auto-detected formats
- Syslog Parser Split RFC 3164 and RFC 5424 syslog with PRI, facility and severity
- Log Viewer Format and filter JSON, logfmt, Kubernetes and Docker logs as tables
- Stack Trace Formatter Parse and organize stack traces from multiple languages with frames
- Traceparent Parser Decode traceparent headers and validate W3C Trace Context format
- PromQL formatter Check PromQL syntax and test vector selectors against pasted metrics without live Prometheus
Frontend & Mobile
Format HTML and CSS, generate CSS effects, check color contrast, test SEO files and debug iOS and Android config.
Images, SVG & Icons 5 tools
- SVG optimizer Optimize static SVG by formatting, minifying or trimming metadata
- Favicon generator Generate favicon.ico, PNG sizes and webmanifest from one image
- Image converter Convert PNG, JPG, WebP and AVIF in batches with quality control
- Image Metadata Viewer and Remover Inspect and remove EXIF, GPS, camera and XMP data from images
- Image resizer and cropper Resize and crop JPG, PNG and WebP with live crop preview
HTML / CSS Dev Tools 12 tools
- HTML formatter and checker Make HTML readable with cautious indentation and structure checking
- CSS formatter Format or minify CSS while keeping selector order and detecting syntax errors
- JavaScript / TypeScript formatter Format JavaScript, TypeScript, JSX and TSX with minify option
- HTML and Markdown Converter Convert between HTML and Markdown preserving structure and links
- CSS Grid / Flex layout generator Paint Grid or Flexbox layouts visually, then copy the generated HTML and CSS
- CSS responsive units and clamp Convert CSS units and generate responsive clamp() expressions
- CSS specificity calculator Compare selector specificity scores and inspect :is() and :where()
- CSS gradient generator Design linear, radial or conic gradients with live color preview
- CSS effects generator Layer box shadows, borders, transforms and filters with live preview
- CSS Clip-path Generator Draw polygon masks visually and export CSS clip-path declarations
- Cubic bezier editor Tune timing curves by dragging handles and preview CSS animations
Color & Accessibility 5 tools
- Color Blindness Simulator Compare colors and images with simulated vision models side by side
- Color converter See one color in seven formats: HEX, RGB, HSL, HSV, CMYK, Lab and OKLCH
- Color palette generator Build color harmonies and tints from a base color with CSS export
- Color Contrast Checker Verify text foreground and background color contrast against WCAG
- APCA contrast calculator Calculate APCA perceptual contrast for readable text on screens
Site & SEO Dev Tools 5 tools
- robots.txt generator and tester Test crawl rules against one URL before deploying your robots.txt file
- Hreflang checker Compare hreflang links across language pages and find missing edges
- Meta tag generator Draft title, description and Open Graph tags with sharing previews
- Sitemap generator and validator Generate XML sitemaps from URL lists and validate existing sitemap files
- JSON-LD structured data helper Validate JSON-LD structure and compare terms against an offline Schema.org snapshot
iOS / Android Dev Tools 10 tools
- Provisioning Profile Viewer Inspect iOS provisioning profile entitlements and device lists
- AASA Validator Test Apple App Site Association rules against HTTPS URLs
- APNs token formatter Format APNs tokens between hex text and decimal byte arrays
- Android manifest viewer Extract Android manifest permissions, components and intent filters
- Android App Links validator Validate assetlinks.json against package and signing certificate
- ADB command builder Build adb commands for install, logcat, screenshots and file transfers
- Deep link builder Compose custom scheme or Android Intent URIs with query encoding
- Bundle ID / Android package validator Check iOS Bundle IDs and Android package names segment by segment
- Mobile unit converter Convert dp, sp, pt and px between Android and iOS display scales
Protocols & AI
Decode binary protocols and serialization formats, inspect LLM and MCP payloads, and look up developer references.
Protocols & Binary Serialization 14 tools
- Protobuf Schema tools Format proto3 schemas, check field numbers and browse structure trees
- Protobuf Wire / Varint tool Decode wire format messages showing byte offsets or parse with .proto
- MessagePack Decoder Decode MessagePack from hex, base64 or files preserving binary types
- CBOR to JSON converter Decode CBOR from hex or base64 with byte-offset tree and type preservation
- BSON / Extended JSON tools Inspect BSON documents and export to Extended JSON preserving typed values
- ASN.1 / DER / BER / TLV viewer Decode ASN.1 BER/DER structures to trace byte boundaries and tags
- WebSocket frame decoder Decode WebSocket hex captures with header and payload inspection
- Redis RESP parser Parse Redis RESP wire data to inspect protocol frames and types
- Modbus CRC calculator Calculate or verify CRC-16 bytes for Modbus RTU frame validation
- NMEA sentence parser Extract fields from GPS NMEA sentences with checksum validation
- MQTT topic matcher Test MQTT subscription filters and see which topics match
- MQTT / AMQP / WebSocket URI Parse MQTT, AMQP and WebSocket connection URIs without connecting
- Kafka partition calculator Calculate which partition a Kafka key hashes to with Murmur2
AI / LLM Dev Tools 7 tools
- Structured output schema checker Validate structured output schemas against OpenAI and Gemini constraints
- JSONL viewer Find line errors in JSONL files and inspect records without parsing failures
- JSON-RPC message viewer Pair JSON-RPC requests and responses by ID across message batches
- SSE parser Parse server-sent events and identify which blocks actually dispatch
- RAG text chunker Split text into chunks by character count, token estimate or Markdown headings
- Token counter Count tokens using o200k_base or cl100k_base with ID inspection and context
- Vector similarity calculator Compare vector similarity using cosine, dot product and Euclidean distance
Developer Reference 9 tools
- HTTP status codes Look up HTTP status codes with response shapes and first checks
- HTTP methods, headers and MIME reference Search HTTP methods, headers and MIME types in one curated index
- Accessibility and ARIA reference Search ARIA roles and attributes with implementation examples
- JWT claims and OAuth errors Look up JWT claims and OAuth error codes with response examples
- ASCII, Unicode and HTML entity reference Browse ASCII, Unicode names and HTML entities in one searchable index
- Developer cheat sheets Find Git, regex, Cron and command syntax with sourced examples
- Linux constants and exit status Search Linux exit codes, signals, errno and syscall numbers
- Network protocols and ports Browse TCP/UDP ports, DNS types, IP numbers and ICMP with sources
- Platform and region reference Search IANA time zones, locales, AWS regions and platform codes
No tool matches that filter. Try a format name such as "json", "csv" or "yaml".
Developer tools directory FAQ
How the list is organized and what the tools do with your data.
How are the developer tools organized?
Tools are grouped into eight topics, such as Data & Formats or Dev & Ops, and each topic is split into focused categories like JSON, Kubernetes or JWT. A tool that fits two categories, such as CSV to JSON, is listed on both category pages but only once here.
Which tools send data over the network?
Only the tools whose job needs it: DNS lookup, IP and ASN lookup, the network checker, the SSL checker, the HTTP client, the HTTP header checker, the redirect checker, the webhook tester and the email DNS checker. They run when you start them. Everything else processes input in your browser.
Are all of these tools free?
Yes. There is no paid tier and no account. Tools that depend on an external service have rate limits so the service stays available for everyone.
Can I find a tool without scrolling the whole list?
Yes. Type in the filter above the list, or use the search shortcut in the header on any page. Both match tool names, formats and category names.
Don't see the tool you need?