Text & documents
Encoder/DecoderURL, Base64, HTML
Text convertercamelCase, snake_case...
Text DiffCompare two texts
LaTeXPreview mathematical formulas
MarkdownReal-time preview
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String escaperJS, JSON, SQL, Regex, HTML, URL
Unicode / ASCIICharacter information
Numbers & maths
CalculatorExpressions, calculation sheet and plots
StatisticsCalculator, distributions, simulators
Physics SimulatorPendulum, energy, integrators
Base converterBase 2 to 64
Unit systembits, bytes, SI, IEC
Subnet / CIDRNetwork calculator
Timestamp and datesUnix, time zones, formats
Date calculatorDays between dates, exact age, day of the week
Data & formats
Format converterJSON, YAML, Properties, ENV, CSV
JSON FormatterFormat and validate JSON
Regex TesterRegular expressions
JSON DiffStructurally compare two JSONs
Code formatterSQL, CSS, HTML, JavaScript
DB StudioVisual Postgres database in the browser
SQL LabValidate, run and optimize SQL with real Postgres
Giant file viewerOpen huge CSV/logs without loading them
Visual ETL flowTransform data by chaining nodes
Log analyzerMake sense of a log: traces, patterns and AI reduction
Knowledge graphRDF, SPARQL and ontologies
Atoms and chemistryPeriodic table, orbitals and valence shell
Security
Text anonymizerRedact PII and secrets (reversible)
JWT InspectorDecode JWT tokens
Auth flowsBasic, JWT and OAuth2 step by step
Hash generatorSHA-256, SHA-384, SHA-512
Password & UUID generatorPasswords and UUIDs
Development & DevOps
CronGenerator and validator
Docker → ComposeConvert docker run to Compose
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Linux: permissions and userschmod, chown, useradd and groups
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Random dataNames, emails, IPs, UUIDs...
ElectronicsOhm's law, series/parallel resistors
From the transistor to the chipFrom a cell's noise margin to the clock: SRAM, read path, IR drop, standard cell and setup/hold
Logic GatesAND, OR, NOT and more gate simulator
Architecture SimulatorDiagram CI/CD, cloud, AI/MCP and simulate load
Quantum simulatorQubits, gates, superposition and entanglement
HammingError detection
Nginx/Apache SPA configGenerate config to serve a SPA
SemverSemantic version ranges
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Cert inspectorAnalyse X.509 certificates in PEM format
Rate LimiterSimulate Token Bucket and Fixed Window
Assembly simulatorSimplified MIPS ISA · step-by-step · registers & memory
Context ForgePack and shield your project for AI
Visual terminalClick and get the command: Linux, macOS, PowerShell
Artificial Intelligence
LLM costsSimulate monthly spend
AgentsSpec, permissions, verification and evals
Local AI cameraDetects objects and alerts, without uploading anything
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Does this text say anything?How much you can cut without losing a single idea
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Probability for AIDistributions, softmax, Bayes and entropy
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Dimensionality reducerPCA, t-SNE and UMAP, live
Confusion matrix & ROCThreshold, precision/recall, ROC/AUC, PR
Clustering (k-means, DBSCAN)Discover groups without labels
Attention visualizerWhat each word looks at in a transformer
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Decision treeDecision regions + the tree
DiffusionThe noise behind Stable Diffusion
Regression & MLELeast squares, overfitting, ridge
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Hypothesis testingp-values, t-test, χ², ANOVA and power
OCR — Image to textExtract text from images, 100% local
Finance
InflationYear-by-year purchasing power erosion
Economy simulatorFirms, prices, monopolies and limited resources
Compound interestCapital + contributions + compound interest
Mortgage / loanMonthly payment and French amortization schedule
Split expensesWho owes whom and how much
Health & Wellness
BMI & healthBMI, ideal weight, BMR and sleep cycles
Productivity
PomodoroTime-block work technique
StopwatchWith laps, stages and history
Games & Entertainment
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Random pickerPick a random item from a list
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Multimedia & design
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Meeting costHow much does each meeting really cost?
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UTM BuilderBuild and decode URLs with UTM parameters
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Project workshopSimulate your Makefile: what it rebuilds and why
Project X-rayWhat Spring will do with your code, and which dependencies are stale
Test auditorOf these passing tests, which ones cannot fail?
Manuscript auditorWhich numbers in your paper or thesis don't add up
How to use
Basic usage

Calculate the growth of an investment with compound interest. Enter the initial capital, the annual return, the investment years and the optional monthly contribution.

How it is calculated

Compound interest reinvests the earned interest following the formula A = P(1 + r/n)^(nt), so earnings in turn generate new earnings.

Month-by-month detail

Expand each year in the table to see the month-by-month detail of the balance, contributions and interest.

Compound interestCapital + contributions + compound interest
Compound interestCalculate investment growth with periodic contributions
Initial investment
Expected annual return rate
Investment duration
Additional amount each month
Total accumulated92,783.93€
Total invested34,000.00€
Generated interest58,783.93€
YearOpening balanceContributionsInterestClosing balance
110,000.00€1,200.00€769.39€11,969.39€
211,969.39€1,200.00€911.76€14,081.14€
314,081.14€1,200.00€1,064.41€16,345.56€
416,345.56€1,200.00€1,228.11€18,773.67€
518,773.67€1,200.00€1,403.64€21,377.31€
621,377.31€1,200.00€1,591.85€24,169.16€
724,169.16€1,200.00€1,793.68€27,162.84€
827,162.84€1,200.00€2,010.09€30,372.93€
930,372.93€1,200.00€2,242.15€33,815.08€
1033,815.08€1,200.00€2,490.98€37,506.06€
1137,506.06€1,200.00€2,757.80€41,463.86€
1241,463.86€1,200.00€3,043.91€45,707.78€
1345,707.78€1,200.00€3,350.71€50,258.48€
1450,258.48€1,200.00€3,679.68€55,138.16€
1555,138.16€1,200.00€4,032.43€60,370.59€
1660,370.59€1,200.00€4,410.68€65,981.27€
1765,981.27€1,200.00€4,816.28€71,997.55€
1871,997.55€1,200.00€5,251.20€78,448.75€
1978,448.75€1,200.00€5,717.55€85,366.30€
2085,366.30€1,200.00€6,217.62€92,783.93€