Technical documentation template
The documentation structure that covers what developers actually need to know.
Technical documentation serves two audiences: new developers joining the project and future-you who forgot how something works. This template covers both by organizing documentation into sections that answer the most common questions.
Not every project needs every section. Start with the ones most relevant to your situation and add more as needed.
System overview
What the system does, who it serves, and the high-level technical approach. Include a 1-paragraph summary and a system context diagram.
Example
ReportGen is an internal tool that generates quarterly business reports from data warehouse queries. It is used by the finance team (10 users) and runs on a schedule every Monday at 6 AM UTC. The system queries Snowflake, transforms data with Python scripts, generates PDF reports, and emails them via SendGrid.
Architecture
Detailed architecture documentation including component descriptions, communication patterns, and deployment topology.
Example
Components: - Scheduler: AWS EventBridge rule triggers a Lambda function every Monday at 6 AM UTC. - Data fetcher: Lambda function queries Snowflake via the Python connector, stores results in S3. - Report generator: Separate Lambda reads S3 data, generates PDF using ReportLab, uploads to S3. - Emailer: SNS notification triggers a Lambda that sends the PDF via SendGrid. Communication: All components communicate asynchronously via S3 (data) and SNS (events). No direct API calls between components.
API reference
For projects with APIs: document every endpoint with method, path, parameters, request/response body, authentication, and error codes.
Example
POST /api/reports/generate Triggers an on-demand report generation. Requires admin authentication. Request body: { "quarter": "Q1", "year": 2026, "format": "pdf" | "csv" } Response (202 Accepted): { "jobId": "rpt_abc123", "status": "queued", "estimatedTime": "120s" } Errors: - 400: Invalid quarter/year combination - 401: Missing or invalid authentication - 429: Rate limited (max 5 requests per hour)
Data model
Database schema documentation including tables, columns, relationships, and constraints.
Example
reports table: - id (uuid, PK) - quarter (varchar, not null) - "Q1", "Q2", "Q3", "Q4" - year (int, not null) - status (varchar, not null) - "queued", "processing", "completed", "failed" - s3_key (varchar, nullable) - S3 path to generated report - created_at (timestamp) - completed_at (timestamp, nullable) Indexes: (quarter, year) unique, (status) for job queue queries
Configuration and environment
All configuration values, environment variables, and feature flags with descriptions and default values.
Example
| Variable | Required | Default | Description | | --- | --- | --- | --- | | SNOWFLAKE_ACCOUNT | Yes | - | Snowflake account identifier | | SNOWFLAKE_USER | Yes | - | Service account username | | SENDGRID_API_KEY | Yes | - | Email delivery API key | | REPORT_S3_BUCKET | Yes | - | S3 bucket for report storage | | MAX_CONCURRENT_REPORTS | No | 3 | Maximum parallel report jobs |
Deployment
How to deploy the application, including CI/CD pipeline, infrastructure requirements, and rollback procedures.
Example
Deployment is managed via AWS CDK (infrastructure as code in cdk/ directory). 1. Infrastructure changes: cdk deploy --all 2. Code changes: Push to main branch triggers GitHub Actions pipeline that builds, tests, and deploys Lambda functions. 3. Rollback: Each Lambda has version aliases. Run ./scripts/rollback.sh [function-name] [version] to point the alias to a previous version.
Monitoring and alerting
What monitoring is in place, what alerts exist, and what to do when they fire.
Example
Monitoring: - CloudWatch metrics for Lambda invocation count, duration, and errors. - S3 event notifications confirm report uploads. - SendGrid delivery webhooks confirm email delivery. Alerts: - Lambda error rate > 5% in 15 minutes -> PagerDuty alert to on-call. - Report generation time > 10 minutes -> Slack notification to #reports channel. - SendGrid bounce rate > 2% -> Email to finance-ops@company.com.
Maintenance procedures
Regular maintenance tasks, their frequency, and how to perform them.
Example
Weekly: Check CloudWatch dashboards for error spikes. Monthly: Review S3 storage costs. Reports older than 12 months are archived to Glacier. Quarterly: Update Python dependencies. Run pip audit and update any vulnerable packages. Annually: Rotate Snowflake service account credentials and update environment variables.
Automate this with CodeDashboard
CodeDashboard generates the system overview, architecture, API reference, and data model sections automatically from the codebase. For the remaining sections (deployment, monitoring, maintenance), you need manual documentation because these depend on infrastructure and operational procedures that are not fully captured in code.
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