S3 File Viewer

A web app for browsing S3 buckets and querying text files with SQL. Built with Go, HTMX, the AWS SDK, and DuckDB.

Features

• Browse S3 buckets with folder-style prefix navigation
• View .csv and .txt files only
• Inspect column names and types for tabular files
• Run SQL queries against a file using DuckDB (via the data view)
• Raw text preview fallback for unstructured files

Prerequisites

• Go 1.23+
• AWS credentials configured via the default credential chain (environment variables, ~/.aws/credentials, or IAM role)
• AWS user must have AmazonS3ReadOnlyAccess permission (only readonly is enough)
• Network access on first run (DuckDB downloads the httpfs extension)

Configuration

Run locally

export AWS_REGION=us-east-1
go run ./cmd/server

Open http://localhost:8080, enter a bucket name, and browse.

Usage

1. Home — Enter a bucket name and optional prefix, then click Browse.
2. Browse — Click folders to navigate; click .csv or .txt files to open them. Other file types are listed but not viewable.
3. File view — For tabular files:
   • Columns pane loads automatically with schema info
   • SQL Query pane runs queries against the data view (e.g. SELECT * FROM data LIMIT 100)
   • Results pane shows query output

For unstructured text files, a raw preview is shown instead of the SQL interface.

SQL safety

• Only SELECT queries are allowed
• Multi-statement queries (semicolons) are rejected
• Destructive keywords (DROP, INSERT, CREATE, etc.) are blocked
• Results are capped at MAX_QUERY_ROWS

Project structure

cmd/server/          HTTP server entrypoint
internal/config/     Environment configuration
internal/s3/         AWS S3 listing and object reads
internal/duckdb/     DuckDB pool, schema, and query execution
internal/files/      Text file detection and reader selection
internal/handlers/   HTTP handlers, templates, and static assets