sqlfmt

sqlfmt is a PostgreSQL formatter with command-line, browser, and editor workflows, plus tools for comparing and inspecting EXPLAIN plans. It is best suited to PostgreSQL users who want a consistent style and scriptable checks; its narrow dialect scope and best-effort handling of some syntax make it a poor fit for mixed-dialect or unusually complex SQL.

Overview

sqlfmt uses a river-aligned style: clause keywords are padded to a shared column. That gives SQL a consistent visual structure, but teams must be willing to adopt that particular style rather than choose among presets. The style draws on 343 SQL files from The Art of PostgreSQL query corpus, and the tool is intended for that book and its courses as well as standalone formatting.

The CLI reads files or standard input and writes formatted SQL to standard output. It can also rewrite files in place, list files that need changes, and produce unified diffs. Those modes suit both individual cleanup and review or CI workflows. PostgreSQL is the only supported dialect, and deeply nested subqueries and unusual upsert or DDL forms are best-effort cases; review those rewrites rather than applying them blindly.

Key features

Formatting across workflows

The browser formatter runs sqlfmt through WebAssembly without requiring installation. The repository also provides an Emacs mode and Vim integration through formatprg and equalprg, and the Go format subpackage exposes Format(io.Reader) (string, error) for Go programs. That range makes sqlfmt practical for users who want one formatter in an editor, a shell, or application code.

The WebAssembly build exposes sqlfmt.format(sql) and sqlfmt.version to browser JavaScript. A TinyGo and wasm-opt build is about 330 KB, compared with about 2.9 MB for the standard Go WebAssembly target, a useful reduction for browser delivery. Building WebAssembly requires tinygo and wasm-opt on PATH, so that compact output is less relevant to users who only need the hosted formatter or CLI.

PostgreSQL plan tools

The explain subcommand formats PostgreSQL EXPLAIN output and can provide advice, structural diffs, and canonical operations. Advice describes join order and method, access method, and parallelism, but not costs, row estimates, or timing; it helps explain plan shape, not diagnose performance by itself.

explain diff exits 0 for structurally identical plans and 1 when their structures differ, making it useful in scripts and CI. The -canonical option normalizes ordering and schema-qualification differences when comparing advice from different sources. These are focused inspection tools, not a substitute for runtime metrics.

Pricing

sqlfmt is free. The Browser formatter plan costs nothing and runs in the browser via WebAssembly with no installation required. The CLI, editor integrations, and Go library are also part of the project, so there is no paid tier to unlock those workflows.

Platforms

sqlfmt supports API, Linux, self-hosted, and web use. The browser formatter needs no local installation; the CLI and editor integrations suit Linux and self-hosted workflows. The project also supplies a WebAssembly API for browser JavaScript. PostgreSQL is the sole supported SQL dialect.

Who it's for

sqlfmt is a good choice for PostgreSQL developers who want a single formatter for shell scripts, editor use, browser formatting, or Go applications, and for teams that want structural plan comparisons in CI. It is less suitable where SQL spans multiple dialects or relies heavily on deeply nested queries and unusual upsert or DDL syntax. Its PostgreSQL-specific plan advice will also be of limited use to teams seeking cost, row-estimate, or timing analysis from that output.

Pros and cons

Pros: Free across browser and CLI workflows, with no paid tier gating the core tools.

Pros: File, stdin, in-place, and diff modes support both manual formatting and automated checks.

Pros: EXPLAIN formatting and structural comparison add a CI-friendly way to detect plan-shape changes.

Pros: Emacs, Vim, Go, and browser JavaScript interfaces extend use beyond the command line.

Cons: PostgreSQL-only support rules it out for projects that need a shared formatter across dialects.

Cons: Deeply nested subqueries and unusual upsert or DDL forms receive best-effort formatting, calling for review.

Cons: Plan advice omits costs, row estimates, and timing, limiting its value for performance diagnosis.

Alternatives

For other free SQL tools, browse SQL Linters and Formatters. Consider SQLCheck as another free command-line option, or Squawk if its broader platform support matters. Poor SQL is a free alternative with online and offline formatting and an SSMS/Visual Studio plugin; its open-source library is AGPL-licensed. Sqruff is another free option with web, self-hosted, and editor-extension platforms. TSQLLint is free and installable with dotnet-tool, Homebrew, or NPM. JSQLFormatter is another free choice for Linux, macOS, Windows, and self-hosted use. Sleek is a free open-source SQL formatter with editor-extension support. Choose SQL Formatter for its free formatting library and browser demo; it is MIT licensed.

Verdict

Choose sqlfmt if your SQL is PostgreSQL and you want a free, consistent formatter that works in scripts, editors, browsers, and CI, with plan-shape comparisons as a useful extra. Look elsewhere for multi-dialect coverage, or if complex nested queries and unusual DDL or upsert syntax need more than best-effort formatting.