proto-tap: see every query, request, and call your app sends

Three steps. No code changes.

Start the proxy

The daemon forwards traffic to your backend and captures it on the way through.

DATABASE_URL="postgres://user:pass@localhost:5432/db?sslmode=disable" \
  sql-tapd --driver=postgres --listen=:5433 --upstream=localhost:5432

Point your app at it

Change the port and nothing else. sql-tapd speaks the native wire protocol, so your driver doesn't notice.
```
DATABASE_URL="postgres://user:pass@localhost:5433/db?sslmode=disable"
```
Watch the traffic

Add --http=:8080 to the daemon to get the Web UI in your browser too.
```
sql-tap localhost:9091
```

sql-tap

For PostgreSQL, MySQL, and TiDB. It reads the database wire protocol, so you see what actually reached the database, whatever your ORM generated.

Inspect each query with its bound arguments, rows affected, and transaction
Run EXPLAIN or EXPLAIN ANALYZE from the list, and edit the query first to try a fix
Flag N+1 and slow queries as they happen
Filter with d>100ms, op:select, error, or n+1

sql-tap on GitHub

sql-tap filtered to n+1, listing twelve runs of the same SELECT, each marked N+1

Fail the build on N+1 and slow queries

Run your tests through the proxy with sql-tap -ci watching. It prints a report when it stops and exits 1 if it found problems.

sql-tap CI Report
=================
Captured: 307 queries

Problems found:
  [N+1]  SELECT name FROM users WHERE id = $1  (detected 18 times)
  [N+1]  SELECT name FROM projects WHERE id = $1  (detected 12 times)
  [SLOW] SELECT pg_sleep(?)  (avg 153ms, 2 occurrences)

Exit: 1 (3 problems found)

http-tap

For anything that speaks HTTP. A reverse proxy in front of your server that records headers, bodies, status codes, and timing for every request.

Read request and response bodies, up to 64 KB each
Edit a captured request in $EDITOR and send it again, or replay it from the browser
Compare endpoints by count, errors, and time
Export captures as JSON or Markdown
Proxy HTTPS upstreams, including self-signed ones

http-tap on GitHub

The http-tap inspector showing a POST request with its headers and JSON bodies

grpc-tap

For gRPC, gRPC-Web, and Connect. An HTTP/2 reverse proxy that records headers, bodies, status codes, and timing for every call.

Capture all three protocols through one port
Read message bodies without your .proto files, by field number
Edit a request body as JSON and resend it
Compare methods by count, errors, and time
Export captures as JSON or Markdown

grpc-tap on GitHub

The grpc-tap inspector showing a Connect call with its headers and bodies by field number

Install

Each cask installs the client and its proxy daemon.

Tool	Captures	Clients	Homebrew
sql-tap	PostgreSQL, MySQL, TiDB	Terminal, browser	`brew install --cask proto-tap/tap/sql-tap`
http-tap	HTTP, HTTPS upstreams	Terminal, browser	`brew install --cask proto-tap/tap/http-tap`
grpc-tap	gRPC, gRPC-Web, Connect	Terminal, browser	`brew install --cask proto-tap/tap/grpc-tap`

With Go, install both binaries. This example is for sql-tap; swap in the tool you want.

go install github.com/proto-tap/sql-tap@latest
go install github.com/proto-tap/sql-tap/cmd/sql-tapd@latest