Free online developer tools

193 tools

Small utilities developers reach for daily: JSON and YAML formatters, Base64 and URL encoders, regex testers, JWT decoders, diff viewers and cron helpers. Prefer tools marked as running in your browser when you paste tokens, keys or production data, because nothing is uploaded.

Showing 25–48 of 193

0.829score
JS Beautifier
beautifier.io
Reformats minified or messy JavaScript, HTML and CSS with indentation settings.
ArtifactNo sign-up★ 9Kdeveloper tools
0.828score
gitignore.io
Toptal
Creates a .gitignore file from templates for operating systems, IDEs and languages.
ArtifactNo sign-up★ 8.8Kdeveloper tools
0.827score
wasm2wat Demo
WebAssembly Community
Disassembles an uploaded .wasm module into readable WebAssembly text.
ArtifactNo sign-up★ 8.2Kdeveloper tools
0.827score
wat2wasm Demo
WebAssembly Community
Assembles WebAssembly text format to a binary module and runs the JavaScript harness.
ArtifactNo sign-up★ 8.2Kdeveloper tools
0.826score
curlconverter
curlconverter
Turns a curl command into equivalent request code in many programming languages.
ArtifactNo sign-up★ 8.2Kdeveloper tools
0.825score
Lightning CSS Playground
Parcel
Transform, prefix and minify CSS against chosen browser targets in the browser.
ArtifactNo sign-up★ 7.7Kdeveloper tools
0.823score
Llama Coder
Nutlope
Describe an app idea and an open model generates a runnable code project with a preview.
ArtifactAINo sign-up★ 7.1Kdeveloper tools
0.821score
AST Explorer
Felix Kling
Parses code with many language parsers and displays the syntax tree for exploring transforms.
ArtifactNo sign-up★ 6.5Kdeveloper tools
0.818score
Regulex
CJex
Draws a JavaScript regular expression as a railroad-style diagram to help you read it.
ArtifactNo sign-up★ 5.8Kdeveloper tools
0.818score
EC2Instances.info
Vantage
Compares Amazon EC2 instance types by specs and price across regions.
ArtifactNo sign-up★ 5.8Kdeveloper tools
0.816score
make real
tldraw
Draw a user interface on a canvas and a vision model turns it into working HTML; uses your own API key.
ArtifactAINo sign-up★ 5.4Kdeveloper tools
0.815score
MQTTX Web
EMQX
Browser MQTT 5.0 client that connects over WebSocket to publish and subscribe to topics.
ArtifactNo sign-up★ 5.1Kdeveloper tools
0.813score
C++ Insights
Andreas Fertig
Shows what the compiler generates behind C++ features by expanding your code into explicit source.
ArtifactNo sign-up★ 4.7Kdeveloper tools
0.812score
readme.so
Katherine Peterson
Drag-and-drop section templates and a Markdown editor for assembling a project README.
ArtifactNo sign-up★ 4.6Kdeveloper tools
0.811score
actionlint Playground
rhysd
Lints GitHub Actions workflow files in the browser using the WebAssembly build of actionlint.
ArtifactNo sign-up★ 4.4Kdeveloper tools
0.807score
Composerize
Composerize
Converts a docker run command into docker-compose YAML.
ArtifactNo sign-up★ 3.8Kdeveloper tools
0.806score
PEV2 PostgreSQL Plan Visualizer
Dalibo
Renders PostgreSQL EXPLAIN output as an annotated tree so slow plan nodes stand out.
ArtifactNo sign-up★ 3.6Kdeveloper tools
0.805score
JSON Schema Faker
json-schema-faker
Generates realistic fake JSON that conforms to a JSON Schema.
ArtifactNo sign-up★ 3.4Kdeveloper tools
0.805score
diff2html
Rodrigo Fernandes
Renders a unified git diff as side-by-side or line-by-line HTML with syntax highlighting.
ArtifactNo sign-up★ 3.4Kdeveloper tools
0.803score
database.build
Supabase community
Postgres running in the browser through PGlite, paired with an AI assistant for schemas, CSV imports and diagrams.
ArtifactAINo sign-upIn-browser★ 2.9Kdeveloper tools
0.800score
pev Postgres EXPLAIN Visualizer
Alex Tatiyants
Draws a PostgreSQL EXPLAIN JSON plan as a tree with cost and time per node.
ArtifactNo sign-up★ 2.8Kdeveloper tools
0.799score
Restfox
Flawid Dsouza
Minimal offline-first HTTP client for the web that organizes requests into collections.
ArtifactNo sign-up★ 2.8Kdeveloper tools
0.799score
PGTune
Alexey Vasiliev
Suggests postgresql.conf settings for given hardware, PostgreSQL version and workload type.
ArtifactNo sign-up★ 2.8Kdeveloper tools
0.790score
DartPad
Dart team
Runs Dart and Flutter snippets in the browser with a console and a live preview pane.
ArtifactNo sign-up★ 1.9Kdeveloper tools