Small tools for small jobs.

Open a tool, get the answer, get back to work. No account, no install, nothing between you and the result.

Private by default. Every tool runs in your browser, and nothing you enter leaves your device.

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Developer

Base64 Encoder / DecoderEncode or decode Base64 for UTF-8 text or raw hex bytes, standard or url-safe.

Chmod CalculatorConvert Unix permissions between checkboxes, octal (755) and symbolic (rwxr-xr-x), including setuid, setgid and sticky.

Cron Expression BuilderBuild or paste a cron expression, read it in plain English, and see the next 10 run times.

CSV ⇄ JSON ConverterConvert CSV to JSON and back, auto-detect delimiters, or change a file's delimiter safely.

Hash GeneratorMD5, SHA-1 and SHA-256/384/512 of text or large files, optional HMAC, and checksum comparison.

HTML Entity EncoderEscape text for HTML, or decode named and numeric character references back to text.

JSON Formatter & ValidatorFormat, minify, sort keys and validate JSON with the exact line and column of any error.

JSONPath TesterRun JSONPath queries with filters against your JSON and see every match with its path.

JWT DecoderInspect a JSON Web Token's header and payload, see expiry as a date, and verify HS/RS/PS/ES signatures locally.

Password GeneratorStrong random passwords or EFF-wordlist passphrases, with entropy shown, generated locally.

Regex TesterTest JavaScript regular expressions with live highlighting, capture groups and replace preview.

SQL FormatterMake dense SQL readable with dialect-aware formatting for PostgreSQL, MySQL, SQLite, SQL Server and more.

Subnet / CIDR CalculatorNetwork, broadcast, host range and mask for an IPv4 CIDR block, splitting into smaller subnets, and IPv6 prefixes.

Unix Timestamp ConverterConvert Unix seconds, ms, µs or ns (auto-detected) to ISO 8601, RFC 2822 and any time zone, and back.

URL Encoder & ParserPercent-encode or decode text, and split a URL into its parts with editable query parameters.

UUID Generator & InspectorGenerate v4 or time-ordered v7 UUIDs in bulk, and decode the version, variant and timestamp of any UUID.

XML FormatterPretty-print or minify XML and check that it's well-formed, with the line of the first error.

YAML Validator & ConverterValidate YAML with the exact line of any error, and convert YAML to JSON or JSON to YAML.

Text

[all 5]

Lorem Ipsum GeneratorPlaceholder text by words, sentences or paragraphs, as plain text or HTML paragraphs.

Markdown PreviewLive GitHub-flavoured Markdown preview with tables and task lists, and the sanitised HTML to copy.

Markdown Table GeneratorEdit a table in a grid, set column alignment, and get a neatly padded Markdown table; import from CSV, TSV or Markdown.

Number to WordsWrite numbers out in words in French (traditional or 1990 spelling) or English, for cheques, invoices and contracts.

Roman Numeral ConverterConvert between numbers and Roman numerals (1–3999), with strict validation of numerals.

Embedded

[all 12]

ADC / DAC Resolution CalculatorLSB size, code to voltage and back, quantization noise, ideal SNR and ENOB for any resolution and reference.

CRC CalculatorCRC-8/16/32 with common presets (Modbus, CCITT, Ethernet, STM32 hardware CRC) or custom parameters, plus C code.

Duty-Cycle Battery LifeBattery life of a device that wakes, works and sleeps, from active, radio and sleep currents.

LED Resistor CalculatorSeries resistor for one or more LEDs, rounded to a standard value, with power and wattage rating.

Number & Float InspectorSee any value as hex, binary and bytes; inspect int8–int64, fp16, bfloat16, fp32 and fp64 bit by bit.

Ohm's Law CalculatorEnter any two of voltage, current, resistance and power; get the other two.

RC / LC Filter CalculatorRC cutoff frequency and time constant, or LC resonance; solve for any missing component.

Resistor Color CodeRead 4, 5 and 6-band resistor colors, or find the bands for a value.

Timer / PWM CalculatorPrescaler, period and compare values for a PWM frequency and duty cycle on STM32, AVR and RP2040/RP2350.

UART Baud Rate ErrorDivisor register value, real baud rate and error % for STM32, AVR, RP2040/RP2350 and ESP32 UARTs.

Voltage Divider CalculatorSolve a divider's output, or find the best standard-value R1/R2 pair for a target voltage.

Hardware

[all 7]

Battery Runtime CalculatorHow long a battery or bank runs a load, from Ah, voltage, depth of discharge and inverter efficiency.

Generator Wattage CalculatorSize a generator from a list of appliances: running watts plus the largest starting surge, with margin.

Solar Battery Bank SizingBattery bank capacity for a daily load and days of autonomy, with series/parallel battery count.

Solar Panel OutputDaily, monthly and yearly energy from your panels, and how many panels a daily load needs.

UPS Runtime CalculatorEstimate UPS backup time from its batteries and your load in watts or VA, and check the load against the rating.

Voltage Drop CalculatorVoltage drop, % loss and cable heat for a DC, single-phase or three-phase run, in mm² or AWG.

Wire Size CalculatorSmallest metric and AWG conductor that keeps voltage drop under your limit for a given current and length.

AI / ML

[all 3]

LLM Memory / VRAM EstimatorEstimate GPU or device memory for running or fine-tuning an LLM, from weights, KV cache and optimizer state.

Quantization Size CalculatorModel size at fp32, fp16, int8 and int4, and whether weights and activations fit an STM32N6, ESP32, Arduino or Pico.

Tensor Shape CalculatorBuild a CNN layer stack and get each layer's output shape, parameter count and MACs.