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Cheat sheets
122 cheat sheets and notes
All cheat sheets
122 results
- ArticleFree
Idempotency Keys for Reliable HTTP APIs: Semantics, Storage, and Failure Recovery
A rigorous guide to designing idempotency keys for HTTP APIs, including request fingerprints, replay semantics, storage guarantees, TTL, retries, multi-region trade-offs, and recovery from partial failures.
ASP.NET Core
- PDFFree
OAuth, OIDC, JWT and Cookie Security: A .NET Interview Decision Sheet
A nine-page ASP.NET Core security decision guide covering client and flow selection, JWT validation, cookie and browser threats, resource authorization, rotation and ten interview prompts.
9 pages · 99 KB · ASP.NET Core
- ArticleFree
Production Incident Triage for ASP.NET Core APIs: a Practical On-Call Guide
A practical, evidence-driven guide to triaging production incidents in ASP.NET Core APIs: classify symptoms, correlate logs/metrics/traces, mitigate safely, communicate well, and close the loop after recovery.
Testing and Production Engineering
- ArticleFree
Stable Pagination in .NET APIs: Offset Drift, Keyset Cursors, and Tie Breakers
Compare offset drift and keyset cursors with deterministic tie breakers, worked C# examples, and explicit limits around mutations, query context, snapshots, and delivery guarantees.
Data Access in .NET
- ArticleFull Access
C# OOP as Type Design: Types, Members and Relationships
C# OOP is best understood as designing stable, meaningful types and relationships.
C# Language
- ArticleFull Access
Learning C# and .NET: Fundamentals to Advanced Topics
A tour of C# and .NET from the fundamentals to collections, async/await, threading and expression trees.
C# Language
- ArticleFree
Choosing Consistency and Availability in Distributed System Interviews
A practical framework for choosing consistency and availability guarantees from user-visible invariants, failure behavior, latency goals, recovery needs, and operational cost.
Architecture and Design in .NET
- ArticleFull Access
Understanding C# OOP, SOLID Principles, and Design Patterns
An introduction to OOP in C#: the four pillars, the SOLID principles for clean design, and the design patterns they lead to.
Architecture and Design in .NET
- NoteFree
LINQ to Objects Execution and Enumeration Checklist for Interviews
A practical revision lesson on deferred vs immediate execution, repeated enumeration, snapshots, and the interview traps that appear when LINQ to Objects is evaluated more than once.
C# Language
- ArticleFree
Choosing Select or SelectMany in C# LINQ with Order-Line Examples
Learn when to use Select versus SelectMany in LINQ by modeling orders and order lines. This lesson shows projection, flattening, empty inner sequences, and the shape of the resulting data.
C# Language
- PDFFree
Strategy or State? Interview Workbook
A free two-page worksheet with six design scenarios and worked answers on pricing, state transitions, rounding, concurrency and idempotency.
2 pages · 5 KB · Architecture and Design in .NET
- ArticleFree
Enforcing Legal Order Lifecycles with the State Pattern
Model order statuses as explicit State objects, validate all 20 state-command combinations, and distinguish in-memory transition rules from persistence and concurrency safeguards.
Architecture and Design in .NET
- PDFFree
Production-Grade .NET Backend Interview Playbook
A professionally designed seven-page field guide covering DI lifetimes, async cancellation, EF Core diagnosis, idempotency, retries, transaction boundaries, and 16 senior interview scenarios with answers.
7 pages · 35 KB · Testing and Production Engineering
- ArticleFree
How to Diagnose and Fix EF Core N+1 Queries in Production
A production-focused playbook for detecting EF Core N+1 queries, choosing projection or Include deliberately, reading SQL plans, applying scalable pagination, and preventing regressions.
Data Access in .NET
- NoteFull Access
Why Mutating Dictionary Keys Breaks Lookup in C#
Learn why changing equality-relevant fields after inserting an object into Dictionary or HashSet makes lookup unreliable, and how to design safer alternatives for .NET code.
C# Language
- NoteFull Access
Choosing Ordinal Comparers for Dictionary and HashSet
Learn how Dictionary<string,TValue> and HashSet<string> use a string comparer to define lookup and uniqueness, and why ordinal comparers are the safest default for backend keys.
C# Language
- NoteFree
Source generators at a glance
Compile-time source, analyzer references, incremental caching, and what a driver test must assert.
C# Language
- PDFFull Access
ASP.NET Core Integration Testing Workbook
Seven-page workbook with HTTP contract scenarios, database isolation guidance, tenant-denial tests and a release-readiness rubric.
7 pages · 96 KB · Testing and Production Engineering
- NoteFree
Observer and Mediator: A One-Page Decision Note
A compact comparison of independent notifications and coordinated workflows, with an ownership table, failure checklist and short worked design question.
Architecture and Design in .NET
- PDFFree
Observer or Mediator? Design Decisions Workbook
Free two-page PDF with six original open-ended design scenarios and reasoned answers, plus a 24-question online companion covering Observer notifications and Mediator workflow recovery.
2 pages · 6 KB · Architecture and Design in .NET