Apyrn Tools
Free online tools for developers, finance, HR and AI teams
Make invoices, salary slips and HR letters, calculate GST, EMI and income tax, format JSON, test regular expressions, decode JWTs, and estimate AI token costs. There is no sign-up, and everything you type stays in your browser.
44Tools
4Work domains
0Server processing
Flagship planning instruments
Planning tools for AI usage, API design, and enterprise data and integration work.
CalculatorsLLM Token & Cost EstimatorEstimate prompt and output tokens at about 4 characters per token and project monthly LLM API cost in USD from your own rates. Runs in your browser.Enterprise planningAI Prompt GeneratorBuild structured prompts for ChatGPT, Claude or Gemini from templates, with role, context, constraints, variables and output format. Runs in your browser.CalculatorsClaude Code Cost CalculatorEstimate Claude Code costs per task and per month from tokens, USD rates and prompt-cache hits, and compare them with a budget. Runs in your browser.Enterprise planningClaude Schedule GeneratorGenerate Claude Code schedule and loop commands from templates and plain-language frequencies, with optional GitHub Actions YAML. Runs in your browser.Enterprise planningERP Integration Cost CalculatorEstimate ERP integration build cost, timeline, maintenance, reconciliation and 3-year TCO, and compare integration approaches. Runs in your browser.Enterprise planningRAG Chunking OptimizerTest RAG chunk size, overlap and splitting strategy on your own text, preview the chunks, and estimate embedding and retrieval cost. Runs in your browser.Enterprise planningData Silo AuditScore data silo risk from system sprawl, point-to-point integrations, reconciliation effort and duplicated entities. Free, and it runs in your browser.Enterprise planningSupply Chain Data MaturityAnswer eight questions on product, inventory, vendor, order and shipment data for a maturity score out of 100 and a breakdown. Runs in your browser.Enterprise planningCanonical Schema GeneratorMap SAP, Salesforce or Oracle source fields to canonical names and generate a draft JSON or YAML schema with mapping evidence. Runs in your browser.Enterprise planningWebhook Payload InspectorInspect webhook headers and JSON payloads, build the HMAC signing string, and check timestamps against a replay window. Runs entirely in your browser.
Document generators
Draft workplace and business documents from structured inputs.
Document generatorsExperience Certificate GeneratorCreate an experience certificate with tenure, responsibilities, performance note and signatory, then download a PDF. Free and made in your browser.Document generatorsAppointment Letter GeneratorDraft an appointment or offer letter with role terms, CTC breakup, probation and an acceptance block, then download a PDF. Free and made in your browser.Document generatorsRent Agreement GeneratorDraft an 11-month rent agreement with landlord and tenant details, rent, deposit, lock-in, notice and witnesses, then print it. Made in your browser.Document generatorsRelieving Letter GeneratorCreate a relieving letter with resignation and last working day, notice-period check, clearance and settlement dates. Free PDF made in your browser.Document generatorsSalary Slip GeneratorGenerate a salary slip with earnings, deductions, attendance, LOP and net pay, then download a PDF or print it. Free and made in your browser.Document generatorsInvoice GeneratorCreate a GST invoice with line items, HSN/SAC codes, CGST/SGST or IGST split, discounts and bank details, then download a PDF. Made in your browser.Document generatorsQuotation GeneratorCreate a quotation with line items, GST split, validity date, discounts and commercial terms, then download a PDF or print it. Made in your browser.Document generatorsID Card GeneratorCreate an employee, visitor, student or membership ID card with photo, logo, QR code or barcode, then download PDF, PNG or SVG. Made in your browser.Document generatorsHRA Receipt GeneratorGenerate monthly, quarterly or yearly HRA rent receipts with landlord PAN, amount in words and receipt numbers, then print or save a PDF in your browser.
Data utilities
Format, encode, inspect, and test developer data without sending it to a server.
Data utilitiesJWT DecoderDecode a JWT's header and payload, read its claims, and flag expiry, issuer and audience problems. Free, and the token is never sent to a server.Data utilitiesJSON to TOON ConverterConvert JSON to TOON, a compact notation for LLM prompts, convert TOON back to JSON, and estimate the token savings. Free and runs in your browser.Data utilitiesJSON Form BuilderDefine form fields in simple lines, preview the form live, and export the HTML with a matching JSON Schema for validation. Free and made in your browser.Data utilitiesDeveloper Tools WorkspaceDraft an API request with headers, params and a JSON body, get curl and fetch snippets, and test assertions on a sample response. Runs in your browser.
Calculators
Estimate finance, commerce, logistics, and AI usage values.
CalculatorsShipping CalculatorWork out volumetric and chargeable weight from parcel dimensions, then estimate shipping cost with your rate, handling and insurance. Runs in your browser.CalculatorsGST CalculatorAdd or remove GST at the rates in force from 22 Sep 2025 (5%, 18%, 40% and special rates) with a CGST, SGST or IGST split. Free and runs in your browser.CalculatorsCurrency Conversion & FX Fee CalculatorConvert an amount at an exchange rate you enter, then see the effect of FX spread, percentage and fixed fees. Not a live rate feed. Runs in your browser.CalculatorsCommission CalculatorCalculate sales commission for percentage, fixed or tiered plans, with quota accelerators and clawbacks, and see the effective rate. Runs in your browser.CalculatorsProfit Margin CalculatorCalculate profit margin, markup, break-even units and the price for a target margin from cost, price, volume and overhead. Free and runs in your browser.CalculatorsEMI CalculatorCalculate loan EMI, total interest and the amortization schedule, and see how prepayments and fees change the cost. Free and runs in your browser.CalculatorsIncome Tax Calculator FY 2026-27Estimate income tax for FY 2026-27 under the new and old regimes, with the ₹12 lakh rebate, ₹75,000 standard deduction and 4% cess. Runs in your browser.CalculatorsCompound Interest CalculatorSee how savings grow with compound interest and monthly deposits, choose the compounding frequency, and adjust for tax and inflation. Runs in your browser.CalculatorsROI CalculatorCalculate return on investment, annualized ROI, NPV at your discount rate, and payback period from yearly cash flows. Free and runs in your browser.CalculatorsAdvanced Loan SimulatorModel a business loan with a moratorium, capitalized or serviced interest, an upfront subsidy and fees, and see the EMI and schedule. Runs in your browser.
Enterprise planning
Use lightweight worksheets for API, data, and integration planning.
Enterprise planningBusiness Credit Risk Worksheet (DSCR)Calculate DSCR and debt-to-income for a business loan and score risk from vintage, industry, repayment history and collateral. Runs in your browser.Enterprise planningBusiness Data WorksheetDefine an entity's owner, sources, identifiers, canonical fields, quality rules and consumers, and export a draft JSON Schema. Runs in your browser.
Utility shelf
Quick developer utilities for hashing, barcodes, cron schedules, JSON, regular expressions, Base64, number bases, and API responses.
Data utilitiesHash GeneratorGenerate SHA-256, SHA-512, SHA-1 and MD5 hashes of any text and check them against an expected checksum. Free, and the text never leaves your browser.Data utilitiesBarcode GeneratorCreate Code 128, EAN-13, UPC or QR code labels, check the value fits the format, and download a PNG or SVG to print. Free and made in your browser.Data utilitiesCron GeneratorBuild a cron expression from presets or five fields, read it in plain English, and preview the next run times. Free and works entirely in your browser.Data utilitiesJSON FormatterFormat, validate, minify and sort JSON online, with the exact parser error when it is invalid. Free, and your JSON never leaves your browser.Data utilitiesRegex TesterTest JavaScript regular expressions with flags, see every match and capture group, and preview replacements. Free, and your text stays in your browser.Data utilitiesBase64 EncoderEncode text to Base64 or decode it back, with UTF-8 support and ready-to-paste data URIs for CSS and HTML. Free, and nothing leaves your browser.Data utilitiesNumber ConverterConvert numbers between binary, octal, decimal and hexadecimal, with 8- to 64-bit word sizes and two's complement. Free and works in your browser.Data utilitiesAPI Response & XML FormatterFormat or minify XML and JSON API responses, and check validity, top-level keys, nesting depth and size. Free, and responses stay in your browser.Data utilitiesEditorial Clarity CheckerCheck writing for repeated words, uniform sentence lengths and stock phrases, with practical edits. Runs in your browser; it is not an AI detector.
Built by Apyrn
Enterprise integration and Business API products
Apyrn Tools is the free workbench from Apyrn, the company building stable, governed Business APIs over the enterprise systems you already run.