The standard library ships 37 canonical modules. They are not loaded by default - import them when you need them.
| Module | Import | Purpose |
|---|---|---|
| Access | import access | Capability, role, audit, and rate-limit primitives for public API authorization |
| API Context | import api_context | Typed request metadata, verified identity, capability helpers, idempotency key, request ID |
| API Response | import api_response | JSON response envelope helpers (ok_object, error_object, paging envelopes) |
| Auth | import auth | In-memory and SQLite auth services, OIDC provider configuration, signed-cookie settings |
| Bytes | import bytes | Binary data, encoding/decoding (base64, hex) |
| CLI | import cli | Command-line argument parsing |
| Collections | from collections import ... | List, dict, and set operations (map, filter, reduce, keys, values, etc.) |
| Config | import config | Deployed app config and secrets through Via's workload-identity-bound config server |
| Content | import content | Safe public content domain types (IssueTitle, MarkdownBody, SafeHtml, PublicUrl, ...) |
| Crypto | import crypto | Hashing, encryption, HMAC, signatures, encoding |
| CSV | import csv | RFC 4180 CSV parsing and writing |
| Decimal | import decimal | Arbitrary-precision decimal arithmetic |
| Environment | import env | Environment variable access |
| Filesystem | import fs | File I/O with typed paths and Result returns |
| HTTP | import http | HTTP client (GET, POST, PUT, DELETE) and static file server |
| JSON | import json | Tree API, streaming, mutable building |
| JSON Schema | import json_schema | Schema-based JSON validation |
| Logging | import log | Log level, sink, capture |
| Mapping | import mapping | Typed row-to-contract mapping helpers (map_rows, json_array_map) |
| Math | import math | Trigonometry, logarithms, rounding, constants |
| Metrics | import metrics | App-authored runtime metrics emitted through the Via runtime |
| Money | import money | Currency-safe monetary arithmetic |
| Paging | import paging | Cursor pagination helpers (PageSlice, page_slice) for handlers |
| Path | import path | Pure path manipulation utilities |
| Process | import process | Subprocess execution, argv, exit, cwd |
| Projection | import projection | Field projection policy for policy-aware JSON construction |
| Random | import random | Random integer generation |
| Scanner | import scanner | Text scanning and pattern matching |
| Service Client | import service_client | Low-level typed service client construction |
| Service Response | import service_response | Typed decoding of ServiceResponse values |
| Template | import template | Pebble-backed template rendering |
| Text | import text | String utilities (split, join, trim, pad, etc.) |
| Time | import time | Instant, Duration, Clock. Typed time API |
| URL | import url | URL parsing, building, and query encoding |
| URL Policy | import url_policy | Public outbound URL, host, DNS, and redirect policy checks |
| UUID | import uuid | UUID v4 generation, parsing, and validation |
| XML | import xml | XML/Atom builder helpers with escaping (xml_element, xml_attr) |
The api_context module also exposes verified identity fields and
helper functions for handler bindings: principal_id, subject, issuer,
session_id, api_token_id, roles, auth_kind, auth_verified,
csrf_verified, plus optional_user(ctx), authenticated_user(ctx),
has_capability(ctx, name), required_capability(ctx, name),
require_csrf(ctx), and request_capabilities(ctx).