High-performance VAST XML validator for Elixir and Erlang.
Validates IAB VAST 2.0–4.3 tags against 108 rules covering required
elements, schema structure, security, deprecated features, and CTV
advisories. Backed by vastlint-core (Rust) via a DirtyCpu NIF -
validation never blocks BEAM schedulers regardless of tag size.
Quick start
iex> {:ok, result} = Vastlint.validate(xml)
iex> result.valid
true
iex> result.summary.errors
0With options
iex> opts = [
...> wrapper_depth: 2,
...> max_wrapper_depth: 5,
...> rule_overrides: %{"VAST-2.0-mediafile-https" => "off"}
...> ]
iex> {:ok, result} = Vastlint.validate(xml, opts)Raising variant
iex> result = Vastlint.validate!(xml)
iex> Enum.filter(result.issues, &(&1.severity == :error))
[]Performance
At production VAST tag sizes (17–44 KB), validation completes in 363–2,104 µs per tag. The NIF runs on dirty CPU schedulers - concurrent calls from many BEAM processes scale linearly with available cores.
See vastlint.org for full benchmark data.
Summary
Functions
Validate a VAST XML binary or string using default settings.
Validate a VAST XML binary or string, raising on failure.
Validate a list of VAST XML binaries in a single NIF dispatch.
Return the vastlint-core library version string, e.g. "0.2.6".
Functions
@spec validate( binary(), keyword() ) :: {:ok, Vastlint.Result.t()} | {:error, term()}
Validate a VAST XML binary or string using default settings.
Returns {:ok, %Vastlint.Result{}} on success, {:error, reason} on
bad input (empty binary, non-UTF-8 bytes).
A result with valid: false is still {:ok, result} - the error tuple
is reserved for call-level failures, not validation failures. Use
result.valid or result.summary.errors to check validation outcome.
Example
iex> {:ok, result} = Vastlint.validate(xml)
iex> result.valid
true@spec validate!( binary(), keyword() ) :: Vastlint.Result.t()
Validate a VAST XML binary or string, raising on failure.
Returns %Vastlint.Result{} directly. Raises Vastlint.ValidationError
if the NIF call itself fails (not if the VAST tag is invalid - a tag with
errors still returns a Result with valid: false).
Example
iex> result = Vastlint.validate!(xml)
iex> result.valid
true@spec validate_batch([binary()]) :: [ok: Vastlint.Result.t(), error: term()]
Validate a list of VAST XML binaries in a single NIF dispatch.
Uses Rayon (Rust's data-parallelism library) to validate all items
concurrently within one dirty-CPU scheduler call, eliminating the
per-call BEAM↔NIF round-trip overhead that limits throughput when
dispatching N individual validate/1 calls from N BEAM processes.
Returns a list of {:ok, %Vastlint.Result{}} or {:error, reason}
tuples, one per input, in the same order as the input list.
When to use
Use validate_batch/1 when you have a burst of tags to validate
concurrently (e.g. an ad-server processing a pod of creatives, or a
pipeline validating a batch upload). For single-tag validation,
validate/1 is simpler.
Example
iex> results = Vastlint.validate_batch([xml1, xml2, xml3])
iex> Enum.all?(results, fn {:ok, r} -> r.valid end)
true@spec version() :: binary()
Return the vastlint-core library version string, e.g. "0.2.6".